Preheat oven to 325F (300F if using a glass baking dish). Separate the yolks from the egg whites. Cream the egg yolks together with the erythritol, liquid stevia, and vanilla.

Once creamed, add the cream cheese and protein powder. Mix well to form a thick batter.

Beat the egg whites together with cream of tartar until stiff peaks form. Fold the egg whites into the egg yolk mixture one half at a time. Pour the batter into a round cake pan.

Prepare the filling by combining the almond flour, cinnamon, butter, Ruled.Me Maple Syrup, and erythritol to create a dough-like mixture. Take half of this mixture and rip it into little pieces; place them in the cake batter, pushing them down with your fingers if they don't sink.

Bake for 20 minutes and then top with the remaining cinnamon filling. Bake for another 20–30 minutes or until a toothpick comes out clean. Let cool for 20 minutes before removing from the cake pan. Enjoy!