For the Light Lemon Cake Layers:
Preheat your oven to 325°F (160°C). Prepare two 8-inch round cake pans by greasing them, then lining the bottoms with parchment paper and greasing the parchment.
In a medium bowl, whisk together the almond flour, protein powder, baking powder, and salt. Set aside.
In a larger bowl, beat the softened butter with the granular sweetener until the mixture is light and fluffy.
Next, beat in the egg whites and vanilla extract until everything is well combined.
Gradually add the dry almond flour mixture to the wet ingredients in two parts, alternating with 1/4 cup of water. If your batter feels too thick, stir in the remaining water.
Divide the batter evenly between your two prepared cake pans, spreading it gently to the edges and smoothing the tops.
Bake for 20 to 25 minutes, or until the cakes are golden brown and feel firm when lightly touched. Let them cool completely in their pans.
For the Luscious Lemon Cream Filling:
In a medium bowl, beat the softened cream cheese until it's wonderfully smooth.
Add 1/2 cup of the powdered sweetener, along with the lemon zest and lemon juice, beating until fully combined.
In a separate bowl, whip the heavy cream with the remaining powdered sweetener (1/4 cup) until stiff peaks form.
Carefully fold the whipped cream into the cream cheese mixture until you have a light and airy filling.
For the Crispy Crumb Garnish:
In a medium bowl, whisk together the almond flour, powdered sweetener, and lemon zest.
Pour in the melted butter and vanilla extract, then toss the mixture until it forms delicate, coarse crumbs.
To Assemble Your Masterpiece:
Place one cooled cake layer on your chosen serving platter.
Set aside about 1/2 cup of your lemon cream filling. Spread the rest of the filling generously over the first cake layer.
Gently place the second cake layer on top of the filling.
Spread the reserved 1/2 cup of cream filling around the sides of the cake.
Using your hands, carefully press the crumb garnish onto the frosted sides of the cake.
For a beautiful finish, dust the top of the cake with a little extra powdered sweetener.
Refrigerate for at least 1 hour to allow the cake to set and firm up before slicing and serving. Enjoy!