For the cake

1. Preheat oven to 350 degrees F.
2. Prepare a 9-inch springform or cake pan by lining the bottom with parchment paper and spraying the bottom and inside with flour-free baking spray. If you’re using a cake pan, create a collar inside of the rim about 5 inches high to protect the cake from browning too quickly. Almond flour tends to burn faster than regular flour.
3. In a large bowl, whisk the almond flour, coconut flour, baking powder, and salt to combine, breaking up any gnarly lumps. Set aside.
4. In a large measuring cup or medium-sized bowl, beat the softened butter with the sweeteners until fluffy, about 2-3 minutes. Add the eggs and beat an additional minute until smooth. Some tiny lumps will remain, but don’t worry about that. Add the sour cream, vanilla and almond extracts, and lemon zest. Beat until smooth, about 30 seconds longer. 
5. Pour the wet mixture into the dry mixture and gently whisk to combine, making sure no dry pockets of flour remain.
6. Set aside to make the crumble.

For the crumble 

1. In a medium-sized bowl, whisk the almond flour, coconut flour, golden monk fruit sweetener, and cinnamon to combine. 
2. Add the softened butter and beat until crumbs form. Make sure all of the dry mixture is moistened by the butter. You should be able to clump it together with your hands to customize the size of your crumbles.
3. Pour the cake batter into the prepared springform pan and even out with a rubber or offset spatula. Top with the fresh blueberries and gently press them into the dough just far enough to create an even layer. Finally, add the crumb mixture on top of the blueberries, squeezing some larger pieces between your fingers and some smaller ones to give the cake some interest. 
4. Bake in the center of your preheated oven for 35-40 minutes.
5. Allow the cake to cool completely to room temperature before serving. Dust with a desired amount of powdered sweetener.
6. You’d be crazy not to eat this with ice cream!