Mix Dry Ingredients. In a bowl, combine almond flour, coconut flour, unsweetened cocoa powder, baking powder, and a pinch of salt. Set aside.
Cream Butter and Sweetener. In another bowl, cream together butter and erythritol until light and fluffy.
Add Eggs and Vanilla. Beat in eggs, one at a time, ensuring each is fully incorporated. Add vanilla extract.
Combine Wet and Dry Mixtures. Gradually add the dry ingredients to the wet mixture, alternating with unsweetened almond milk. Mix until just combined.
Divide Batter and Bake. Divide the batter evenly between the prepared cake pans. Smooth the tops. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.
Cool and Frost. Allow the cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely. Once cooled, frost the cake with your favorite sugar-free frosting.
Decorate and Celebrate. Decorate your Keto Birthday Cake with candles, sprinkles, or any keto-friendly decorations of your choice. Slice, serve, and enjoy the celebration!