Low-Carb Black Widow Cocktail

4.2 stars, average of 84 ratings

By Martina Slajerova, updated October 19 2021
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This spooky low-carb cocktail is perfect for Halloween! I used homemade blackberry-lime syrup and substituted the commonly used simple syrup with powdered Erythritol. There are other options you can try:

Skip the powdered sweetener in the blackberry juice and make your own simple syrup like in this Spicy Low-Carb Margarita. The only drawback of making simple syrup this way is that it may partially crystallise once it's chilled.
You could use NuNaturals Simple Syrup. Apart from plain simple syrup, it's available in several different flavours such as Ginger Syrup which worked wonderfully in my Keto Ginger & Rhubarb Creamsicles. Just remember to use the recommended amount as too much would make your cocktail way too sweet.
Lastly, you can just use a few drops of stevia. NuNaturals are my favourite as they don't taste bitter.

Note that this recipe makes about 2 ¹/₄ cups (530 ml/ 18 fl oz) blackberry juice. This will be enough for 6 cocktails. Fibre is counted partially (25%) as most of the pulp and seeds are discarded.

Looking for a spooky treat? Try my Halloween Keto Pizza, Spooky Eyeball Cookies, Cheesy Keto Spinach Crackers, and even more Halloween Keto Recipes.

0 days, 0 hours, 20 minutes

Hands-on 10 minutes Overall 30 minutes

Serving size cocktail

Allergy information for Low-Carb Black Widow Cocktail

✔ Gluten free

✔ Dairy free

✔ Egg free

✔ Nut free

✔ Nightshade free

✔ Pork free

✔ Avocado free

✔ Coconut free

✔ Fish free

✔ Shellfish free

✔ Beef free

Pescatarian

Vegetarian

Vegan

Nutritional values (per serving, cocktail)

Net carbs4.7 grams

Protein1.1 grams

Fat0.4 grams

Calories166 kcal

Calories from carbs 71%, protein 16%, fat 13%

Total carbs5.7 gramsFiber1 gramsSugars0 gramsSaturated fat0 gramsSodium8 mg(0% RDA)Magnesium17 mg(4% RDA)Potassium135 mg(7% EMR)

Ingredients (makes 1 cocktail)

Homemade blackberry syrup:

450 g fresh or frozen blackberries (1 lb)
¹/₄ cup lime or lemon juice (1-2 pieces)
1 cup water (240 ml/ 8 fl oz)
¹/₂ cup powdered Erythritol or Swerve (80 g/ 2.8 oz)

Each Cocktail:

90 ml homemade blackberry juice (3 fl oz)
¹/₄ cup vodka (60 ml/ 2 fl oz)
ice
Optional: sparkling water (soda water) to top up
Optional: acai powder or freeze-dried berry powder mixed with granulated Erythritol, and fresh blackberries for decoration

Instructions

Place the blackberries in a saucepan.
Add the lime juice and water. Bring to a boil over a medium heat. Boil for 3-5 minutes.
Once softened, mash the blackberries using a fork.
Pour through a fine mesh sieve and using a spoon, press the blackberries through so that only the skins and seeds remain in the sieve.
Pour into a jar. The juice should be quite thick, almost the consistency of syrup.
Note: this recipe makes about 2 ¹/₄ cups (530 ml/ 18 fl oz) blackberry juice. This will be enough for 6 cocktails.
Add the powdered Erythritol and mix until combined. Let it cool and refrigerate until ready. The juice will keep refrigerated for up to 5 days.
To serve, optionally decorate your cocktail glasses by dipping the rims in water and then in a mixture of acai powder (or any berry powder). Fill each glass with ice and pour in the vodka.
Add the sweetened blackberry juice.
Decorate with more fresh blackberries or mint leaves and serve.

Ingredient nutritional breakdown (per serving, cocktail)

Net carbs	Protein	Fat	Calories
Homemade Blackberry Juice (KetoDiet blog)
4.7 g	1.1 g	0.4 g	38 kcal
Vodka, distilled alcoholic beverage (~40% vol)
0 g	0 g	0 g	128 kcal
Ice cubes
0 g	0 g	0 g	0 kcal
Total per serving, cocktail
4.7 g	1.1 g	0.4 g	166 kcal