Preheat and prep: Heat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone mat.

Mix dry ingredients: In a large bowl, whisk together almond flour, coconut flour, baking powder, salt, and 2 teaspoons of cinnamon until evenly combined.

Cream butter and sweetener: In another bowl, beat the softened butter with the granulated sweetener for 1–2 minutes until light and slightly fluffy. Add the egg, egg yolk, and vanilla. Mix until smooth.

Combine: Add the dry mixture to the wet mixture. Stir with a spatula until a soft dough forms. It should be thick but scoopable. If it seems too soft, let it rest 3–5 minutes so the coconut flour can absorb moisture.

Make the coating (optional): In a small dish, combine 1–2 tablespoons sweetener with 1 teaspoon cinnamon. This gives a snickerdoodle-style crust.

Portion the dough: Use a tablespoon or small cookie scoop to form 18–20 balls. Roll each ball lightly in the cinnamon-sweetener mixture if using.

Flatten: Place on the lined baking sheet with a little space between them. Gently press each ball to about 1/2 inch thick. Keto cookies don’t spread much on their own.

Bake: Bake for 8–10 minutes, until the edges look set and the bottoms are lightly golden. The centers should still look a bit soft.

Cool: Let the cookies cool on the baking sheet for 10 minutes to firm up, then transfer to a rack. They’ll set as they cool and become perfectly chewy.

Enjoy: Sprinkle a touch more cinnamon if you like, and serve warm or at room temperature.