Low-Carb Black Widow Cocktail

Low-Carb Black Widow CocktailPin recipeFollow us 50.2k

This spooky low-carb cocktail is perfect for Halloween! I used homemade blackberry juice and substituted the commonly used simple syrup with powdered Erythritol added to the blackberry juice. 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.

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


Nutritional values (per cocktail)

4.7 grams 1 grams 1.1 grams 0.4 grams 0 grams 166 calories
Total Carbs5.7grams
Net Carbs4.7grams
of which Saturated0grams
Magnesium17mg (4% RDA)
Potassium135mg (7% EMR)

Macronutrient ratio: Calories from carbs (71%), protein (16%), fat (13%)

Ingredients (makes 1 cocktail)

Homemade Blackberry Juice:
  • 450 g fresh or frozen blackberries (1 lb)
  • ¼ cup lime or lemon juice (1-2 pieces)
  • 1 cup water (240 ml/ 8 fl oz)
  • ½ cup powdered Erythritol or Swerve (80 g/ 2.8 oz)

Note: Recipe makes about 2 ¼ 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.

Each Cocktail:
  • 90 ml homemade blackberry juice (3 fl oz)
  • ¼ 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


  1. Place the blackberries in a saucepan. Low-Carb Black Widow Cocktail
  2. Add the lime juice and water. Bring to a boil over a medium heat. Boil for 3-5 minutes. Low-Carb Black Widow Cocktail
  3. Once softened, mash the blackberries using a fork.
  4. 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. Low-Carb Black Widow Cocktail
  5. Pour into a jar. The juice should be quite thick, almost the consistency of syrup. Low-Carb Black Widow Cocktail
  6. 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. Low-Carb Black Widow Cocktail
  7. 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. Low-Carb Black Widow Cocktail
  8. Add the sweetened blackberry juice. Low-Carb Black Widow Cocktail
  9. Decorate with more fresh blackberries or mint leaves and serve. Low-Carb Black Widow Cocktail

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