Three ingredients. That's all you need for a batch of chewy, satisfying peanut butter cookies that clock in at just 3g net carbs each. Peanut butter, egg, and sweetener — no flour, no butter, no complicated techniques. These cookies are a vegetarian keto classic for a reason: they're fast, foolproof, and taste like proper peanut butter cookies, not like you're depriving yourself of anything. The natural oils in the peanut butter give them a tender, slightly crumbly texture, and the sweetener caramelises around the edges for those crispy bits everyone fights over. From bowl to cooling rack in 17 minutes, these are the kind of recipe you turn to on a Tuesday evening when you just want something sweet without any fuss.

Why This Works on Keto

Peanut butter is naturally high in fat and protein with moderate carbs, making it a solid keto ingredient. Since the recipe contains no flour of any kind, the carb count stays remarkably low. The egg provides structure and protein without adding carbs, and the erythritol sweetener rounds out the flavour with zero glycaemic impact. These cookies are also naturally dairy-free and gluten-free, making them one of the most allergen-friendly keto cookies you can bake. At 7g of fat and 4g of protein per cookie, they're a macro-friendly sweet treat.

Ingredients

  • 200g natural peanut butter (no added sugar, just peanuts and salt)
  • 1 large egg (about 50g)
  • 80g granular erythritol or monk fruit sweetener

Instructions

  1. Preheat your oven to 180°C (350°F). Line a baking sheet with parchment paper.
  2. In a medium bowl, combine the peanut butter, egg, and sweetener. Stir with a fork or spatula until the mixture is smooth and uniform. It will come together into a thick, slightly sticky dough.
  3. Scoop the dough into 12 equal portions (about 1 heaped tablespoon each). Roll each into a ball and place on the baking sheet, spacing them about 5cm apart.
  4. Use a fork to press a crosshatch pattern into each ball, flattening them to about 1cm thick. Dip the fork in water between cookies to prevent sticking.
  5. Bake for 10–12 minutes until the edges are golden and the tops are just set. The cookies will look slightly underdone in the centre — this is correct. They firm up significantly as they cool.
  6. Let the cookies cool on the baking sheet for at least 10 minutes before transferring to a wire rack. They're very fragile when hot.

Tips & Variations

  • Stir your peanut butter well before measuring — you want the oils fully incorporated for the best texture.
  • For chocolate peanut butter cookies, press 2–3 sugar-free chocolate chips into the top of each cookie before baking.
  • Add 2g of cinnamon and 1g of vanilla extract for a warmer, more complex flavour.
  • These freeze exceptionally well. Layer them between parchment paper in a container and freeze for up to 2 months.
  • For a crunchier cookie, bake an extra 2 minutes. For softer, chewier cookies, pull them at 10 minutes.
  • Swap peanut butter for almond butter or sunflower seed butter — the recipe works with any nut or seed butter.
Why did my cookies fall apart?
The most likely cause is moving them too soon. These cookies are very delicate when hot because they have no flour to hold them together. Let them cool on the baking sheet for a full 10 minutes before trying to move them. They'll firm up considerably.
Can I use crunchy peanut butter?
Absolutely. Crunchy peanut butter adds a nice textural contrast with bits of peanut throughout each cookie. The recipe works identically — just make sure it's a natural variety without added sugar.
Do I need to use natural peanut butter?
Strongly recommended. Commercial peanut butters like Skippy or Jif often contain added sugar, hydrogenated oils, and other ingredients that increase the carb count. Natural peanut butter — the kind where the ingredients list says just "peanuts" and maybe "salt" — keeps the macros clean.