1. Preheat oven to 350 degrees. Spray two 8 inch cake pans with cooking spray and place a round sheet of parchment paper on the bottom of each pan. Set aside.
2. In a large bowl, add almond flour, sweetener, baking powder and salt. Stir to combine. Add egg yolks, sour cream, melted butter, heavy cream or nut milk and vanilla extract. Mix until combined. Set aside.
3. Add egg whites (all 6) into a clean large bowl. Using an electric mixer, start mixing slowly until frothy. Then increase the speed to high and beat until stiff peaks form.
5. Divide the cake batter between the two cake pans. Bake at 350 degrees for 18-20 minutes. Let cool a few minutes before transferring to a wire rack to cool completely. Cut cake into bite sized cubes once cooled.
6. While your cake is baking, add 5 oz strawberries to a sauce pan. Add vanilla syrup. Stir and let cook over medium heat until the berries have release moisture and the sauce has thickened. Remove from heat. Add 2-3 tablespoons of water. Using an hand blender or food processer, puree until smooth.
7. To a large bowl, add heavy whipping cream and sugar free sweetener. Using an electric mixer, mix on low-medium until cream starts to thicken. Add lemon zest and lemon juice. Increase speed to high and beat until stiff peaks form.
8. Add 1/3 lemon whipped cream to the bottom of a trifle dish. Sprinkle 1/2 of the chopped cake on top. Drizzle on 1/2 the syrup lightly over the cake. Top with 1/2 of each berry. Repeat the layers ending with whipped cream.