Preheat the oven to 325 F degrees F. Line the bottoms of two 8-inch round cake pans with parchment paper rounds, then spray with nonstick baking spray. Set aside.

In a large mixing bowl, combine eggs, buttermilk, cooled butter, and vanilla extract.

Mix until thoroughly combined.

In a separate bowl, whisk together the almond flour, coconut flour, powdered erythritol, baking powder, and salt.

Add the dry ingredients to the wet ingredients.

Mix until well combined.

Divide the batter evenly between the prepared baking pans and bake for 20-25 minutes, until a toothpick comes out clean. 

Allow the cakes to cool completely in the pan (at least 30 minutes) before removing. Remove the parchment paper liner and frost as desired.

Add butter and vanilla to a large mixing bowl or a stand mixer (paddle attachment). Mix on high speed until pale and fluffy. 

Add the powdered sweetener, mixing on low speed until incorporated, then on medium speed for 2 minutes until fluffy.

Add vanilla and cream, 1 tablespoon at a time, mixing well between, until your desired smoothness is achieved.

Spread the frosting between the cake layers and on sides using a spatula. Serve or refrigerate until ready to serve.