Preheat the oven to 180C/350F. Line two large baking trays with parchment paper and set aside.
In a large mixing bowl, combine your almond flour, coconut flour, cocoa powder, baking soda, and salt. Mix well. In a separate bowl, add your granulated sweetener, eggs, and butter, and mix well, until smooth. Add the vanilla extract.
Combine your wet and dry ingredients and mix well, until a thick dough remains. Using your hands, form 24 small balls of dough. Place the dough on the two baking trays, and press down into a cookie shape.
Bake the cookies for 12 minutes, before removing from the oven and letting cool on the baking sheets completely. Once cooled, add frosting to half the cookies, before pressing down on each with remaining cookies.
For an eggless or vegan cookie, use double chocolate chip cookies.TO STORE: Store homemade Oreos in the refrigerator, covered, for up to 2 weeks.TO FREEZE: Homemade Oreos are freezer friendly, so store leftovers in a ziplock bag and keep in the freezer for up to 6 months. Thaw overnight in the refrigerator or at room temperature.