Preheat your oven to 325°F. Grease two 8-inch round cake pans and line the bottoms with parchment paper. Whisk together the almond flour, coconut flour, baking powder, and salt in a bowl.
In a large bowl, beat the softened butter and erythritol together until light and fluffy, about 3 minutes. Add the egg yolks one at a time, beating well after each. Mix in the sour cream and vanilla extract.
Fold in the flour mixture until just combined, then stir in the shredded coconut and chopped pecans. In a clean bowl, beat the egg whites with a pinch of salt until stiff peaks form. Gently fold the egg whites into the batter in three additions. Divide the batter between the prepared pans.
Bake for 28 to 32 minutes until the cakes are golden and a toothpick comes out clean. Cool in the pans for 10 minutes, then turn out onto a wire rack to cool completely.
For the frosting, beat the cream cheese and butter together until very smooth and creamy, about 2 minutes. Add the powdered erythritol and vanilla extract and beat until fluffy and light.
Place one cake layer on a plate and spread a generous layer of frosting on top. Set the second cake layer on top and frost the top and sides evenly.
Toast the garnish pecans and coconut flakes in a dry skillet over medium heat for 2 to 3 minutes, stirring constantly, until fragrant and golden. Let them cool, then press them onto the sides and top of the cake. Refrigerate for 1 hour before serving.
