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Low-Carb No Bake Lemon Posset Tart

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Lemon posset tart has long been on my wish list. I love lemon treats like this one because they have the perfect balance of sweet and zingy. Plus there is no baking needed which is what I like in a good summer treat when it's simply too hot to use the oven.

How To Make Low-Carb Lemon Posset Tart

Unlike the traditional version of this delicious summer inspired tart, there is no flour and no sugar in this Keto Lemon Posset Tart.

You'll start with the filling. You only need organic lemons, cream, sweetener and in this recipe we're also using gelatin. This filling will need to cool down to room temperature before you pour it in the pie crust.

Why use gelatin? Classic British lemon posset tart requires no starches and no gelatine in the lemon cream filling to set. That's because the lemon juice is usually enough for it to firm up.

However, I wanted to make this pie foolproof so I decided to add a small amount of gelatine for a better set. Unless you use double cream (higher fat content than heavy whipping cream), you may end up with a runny disaster which is what I wanted to avoid, especially if you're living in the US and use heavy whipping cream.

Just like the filling, the crust is made with just a few ingredients: almonds, sweetener, butter, vanilla and salt. After processing the ingredients into a rough sand-like texture, you'll press the dough into a tart pan to form a crust which you'll then need to chill to harden. After that you'll simply pour in the lemon cream and place the tart in the fridge to fully set.

Finally you'll decorate the tart with berries, fresh mint and a dusting of low-carb sweetener. That's it!

Recipe Tips

This tart is low-carb, keto and egg-free. You can make it nut-free if you use sunflower seeds instead of almonds. You can also make this pie dairy-free if you use coconut cream instead of heavy whipping cream. I have not tested the dairy-free version but it should work as long as you use coconut cream — not coconut milk. If you need to make this tart vegetarian, simply use an equal amount of agar powder instead of the gelatine.

Apart from strawberries and raspberries, you can use blueberries and/or blackberries, or you can leave the pie plain without any berries.

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Hands-on Overall

Serving size 1 slice

Allergy information for Low-Carb No Bake Lemon Posset Tart

✔  Gluten free
✔  Egg free
✔  Nightshade free
✔  Pork free
✔  Avocado free
✔  Coconut free
✔  Fish free
✔  Shellfish free
✔  Beef free

Nutritional values (per serving, 1 slice)

Net carbs7 grams
Protein8.1 grams
Fat44.1 grams
Calories465 kcal
Calories from carbs 6%, protein 7%, fat 87%
Total carbs11.8 gramsFiber4.8 gramsSugars5 gramsSaturated fat19.9 gramsSodium84 mg(4% RDA)Magnesium87 mg(22% RDA)Potassium303 mg(15% EMR)

Ingredients (makes 10 servings)

Lemon cream filling:
  • juice from 3 organic lemons (120 ml/ 4 fl oz)
  • zest from 3 organic lemons
  • 3/4 cup granulated Erythritol or Allulose (150 g/ 5.3 oz)
  • 2 1/2 cups heavy whipping cream (600 ml/ 20.3 fl oz)
  • 2 tsp gelatine powder or agar powder
  • 4 tbsp water (60 ml/ 2 fl oz)
Pie crust:
Pie topping:
  • 3 medium fresh strawberries (75 g/ 2.7 oz)
  • 1 cup fresh raspberries (150 g/ 5.3 oz)
  • Optional: few fresh mint leaves and powdered low-carb sweetener such as Erythritol for dusting


  1. Prepare the lemon filling. Zest and then juice the lemons. Sprinkle the gelatine in a small bowl filled with 4 tablespoons of water. Low-Carb No Bake Lemon Posset Tart
  2. Place the cream, lemon zest and sweetener (Allulose or Erythritol) in a saucepan. Gently heat up until it starts to simmer and the sweetener and the bloomed gelatine and stir until dissolved. Remove from the heat and set aside. Cover with a lid and let it infuse for 10 to 15 minutes. Low-Carb No Bake Lemon Posset Tart
  3. Pour the lemon infused cream through a fine mesh sieve to remove the lemon zest and discard the zest. Stir in the lemon juice and set aside to cool down to room temperature. Low-Carb No Bake Lemon Posset Tart
  4. Meanwhile, prepare the crust. Place the almonds, butter, powdered sweetener (Allulose or Erythritol), vanilla powder (or vanilla extract) and salt into a food processor.
    Note: If you have time, use activated nuts as they are easier to digest. Here's how to activate almonds. Low-Carb No Bake Lemon Posset Tart
  5. Process until you get a sand-like texture. Low-Carb No Bake Lemon Posset Tart
  6. Transfer the dough into a 24 cm (9 inch) pie pan (ideally non stick with a removable bottom) lined with a round 24 cm (9 inch) piece of parchment paper.
  7. Using your hand or a small roller, press the dough down the bottom and up the sides to create an edge. You'll need about 4 cm (1 1/2 inch) edge to hold the filling. Place in the freezer for 15 to 20 minutes for the crust to set. Low-Carb No Bake Lemon Posset Tart
  8. Pour in the cooled lemon cream and carefully place in the fridge until fully set, for 3 to 4 hours. Low-Carb No Bake Lemon Posset Tart
  9. Once the lemon cream has set, decorate the tart with fresh halved strawberries, raspberries and optionally some fresh mint leaves. Low-Carb No Bake Lemon Posset Tart
  10. Optionally, dust with some powdered low-carb sweetener and slice to serve. Low-Carb No Bake Lemon Posset Tart
  11. To store, refrigerate for up to 5 days.
    Note: Although the nutrition facts are calculated with 10 servings, this recipe makes 8 to 12 servings, depending on the size of the slice. Low-Carb No Bake Lemon Posset Tart

Ingredient nutritional breakdown (per serving, 1 slice)

Net carbsProteinFatCalories
Lemon juice, fresh
0.8 g0 g0 g3 kcal
Lemon zest (peel), fresh
0.1 g0 g0 g1 kcal
Erythritol (natural low-carb sweetener)
0.8 g0 g0 g3 kcal
Cream, heavy whipping, pouring, full-fat (30-40% fat)
1.6 g1.1 g22.8 g220 kcal
Gelatin powder, thickening agent, unsweetened
0 g0.6 g0 g2 kcal
Water, still
0 g0 g0 g0 kcal
Almonds, nuts (whole, unblanched)
2.6 g6 g14.3 g166 kcal
Butter, unsalted, grass-fed
0 g0.1 g6.9 g61 kcal
Erythritol (natural low-carb sweetener)
0.1 g0 g0 g0 kcal
Vanilla extract, powder (vanilla bean)
0 g0 g0 g1 kcal
Salt, sea salt
0 g0 g0 g0 kcal
Strawberries, fresh
0.4 g0.1 g0 g2 kcal
Raspberries, fresh
0.7 g0.1 g0.1 g6 kcal
Total per serving, 1 slice
7 g8.1 g44.1 g465 kcal

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Martina Slajerova
Creator of

Martina Slajerova

I changed the way I ate in 2011, when I was diagnosed with Hashimoto’s, an autoimmune disease that affects the thyroid. I had no energy, and I found it more and more difficult to maintain a healthy weight.

That’s when I decided to quit sugar, grains, and processed foods, and to start following a whole-foods-based ketogenic approach to food.

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Comments (7)

Recipes for posset I've seen (the high carb kind) don't have a crust.  They're single servings in small ramekins and you eat it with a spoon, so if the set is a little soft it's not a big deal.  You can cook the cream down a bit if you want to guarantee a harder set.  Adding gelatin would ruin the soft texture and change it into something quite different: a lemon-cream jello, not a posset!  Without a crust the posset is perfect for a low carb adaptation.  

There are a few variations. I've seen possets that look like panna cotta (as you described with no crust and in a jar) and then there are posset tarts (this recipe) which is like a classic pie. The one I've known for years is Mary Berry's recipe which looks like mine. The reason I used gelatin is that this should be an easy to slice tart. If you have a posset in a jar you don't have to worry about the mixture being too soft but with a tart it's a different story. I used just a small amount to make sure it's not too set and still soft.

I hadn't noticed the distinction of "posset tart" from plain "posset".  The posset was originally a drink, so it wouldn't have had a crust.  
Rose Levy Beranbaum claims it won't set properly if more than 3/4 inch thick.  I've never tested this, but have had it set harder on top than on the bottom when in a thin layer. I agree that if you want a sliceable tart, the kind of posset I'm familiar could be a little tricky, though I think it could work with reduced cream.  I must be a gelatin hater because the first thing I think of for a lemon tart is lemon curd thickened only with eggs.   Even when the quantity of gelatin is small it seems like I end up with a texture that's too hard.  (I haven't tried experimenting---decreasing the gelatin in a series of batches to see if there's a good amount.  Maybe I have stronger gelatin.)

I think this texture is pretty good, I have not noticed a "gelatin set" in it like you would in a panna cotta. It's creamier. I know exactly what texture you are referring to, this one doesn't feel that way. You definitely don't want a jello texture. You need to keep the amount at 1-2 teaspoons (might be ok with 1 teaspoon). I tested the classic posset tart without gentian and sadly the set wasn't enough even after a night in the fridge (followed a tested non keto recipe exactly). It might be the type of sweetener that has an impact or the fact that I used heavy whipping cream instead of double cream. If I were you I'd only use 1 teaspoon because I think you may appreciate a softer set which is just like traditional posset 😊

I made some (crustless) possets over the weekend.  I used USA "heavy whipping cream".   I followed the recipe above (with reduced allulose) and got a hard gelatin type set, basically a cream jello.   I made one directly with cream, and a third one with cream that was cooked down from 2 cups to 1 2/3 cups, which is what Cooks Illustrated recommends.  
The reduced cream version set well and was fully set after several hours.  The unreduced cream version is very soft.  I don't know if it would work as a tart, but 24 hours later it is possible to cut it and it forms a clean cut.  
The use of gelatin had another effect I should have expected but did not:  it killed the flavor.  Gelatin (and other hydrocolloids) tend to bind the flavor up to varying degrees, and the gelatin version was bland and lacking in bright lemon flavor compared to the gelatin-free variants.   When I had tasted the mixture before it set it had a better flavor.  
To me, the reduced cream version seems like the right path.  However, it had a problem that I don't understand: the texture was somewhat coarse.  I'm not sure why, or what was contributing to the coarse texture.  

That's a great tip Adrian, I think that reducing the cream is perfect if you want to get a thicker/better set which is what you'd get with double cream here in the UK. I'm almost sure the unreduced version would be too soft. I tried that and it wasn't set after 12 hours. It was ok as a posset in a jar but not sliceable for a tart. As for the flavour, I think it depends on the lemons too as you can always add more by adding more lemon zest. I was told (by my partner) that the flavour was a bit too strong/tart for him. My friends tried it too and they agreed it was strong - but they liked it! So we didn't really have bland tasting posset but I do think that with more gelatin that would be more likely. About the coarse texture.... I'm thinking you may need to use a stick blender to make it smooth as that is what I recommend when making condensed milk. The one made with cream always gets a bit lumpy (the one with coconut milk not as much): How to Make Keto Condensed Milk

I tried another reduced version last night and boiled it more gently.   It came out smooth, but it also seems like it's not reduced as much.  (It didn't set as hard.)  I had a problem where it boiled over when I poured it into a measuring cup to assess the reduction, so then I didn't know how much it had been reduced.  But it may be that just boiling more gently will solve the texture issue.  The Cooks Illustrated recipe doesn't suggest using a blender and I'm not going anywhere near the reduction you'd need for a condensed milk, just a slight reduction, so hopefully using a blender isn't necessary.  I personally like a strong lemon flavor---something has to be pretty tart to be too sour for me.  In the case of the gelatin posset, though, I think it would need either more lemon juice or some other added acid like cream of tartar to boost the tart flavor to get it to match the non-gelatin versions.  (I've added cream of tartar to lemon bars to make them more tart.  Oddly I got a better result doing that than using citric acid, which seems like it would be more correct, but gave a harsher result.)   The thing that's notable is that using a similar amount of lemon juice produced a different tasting result with the gelatin.   Since I was using a single bag of lemons it seems  unlikely that the lemons I used for the first posset were less sour.   And the effect didn't occur until it set.  It seems like we got different results with gelatin, which suggests that the Vital Protein Beef  gelatin I'm using has a higher bloom strength than your gelatin, but reports online seem to indicate that Great Lakes has the same bloom strength----both are 225.