Preheat the oven to 350°F and line a baking sheet with parchment paper.
In a large bowl, combine the butter and erythritol and cream them together with an electric mixer. Add the eggs and vanilla and beat again.
In a separate bowl, combine the coconut flour, almond flour, cocoa powder, baking soda, xanthan gum, salt, and Keto Activate (if using). Add the dry ingredients to the wet ingredients. Mix again with the electric mixer until all ingredients are fully incorporated.
Using a spatula, fold in the chocolate chips.
Use a cookie scoop to scoop cookies onto the baking sheet. Place in the preheated oven and bake for 8-10 minutes.
Remove from the oven and let cool completely on the baking sheet before serving.
If cookies are too flat, chill dough for a half-hour before baking.