Preheat the oven to 350 degrees F, and prepare a 9x5" loaf pan with non stick spray.
Separate the eggs into 2 large bowls.
Add the cream of tarter to the egg whites and beat with an electric mixer until soft peaks form. Set aside.
Add softened butter, vanilla, cream cheese, and stevia to the egg yolks. Mix until well combined. Then add ½ tsp of cinnamon, baking powder and almond flour, stirring until well combined.
In a small bowl, combine the melted butter, erythritol, and the remaining 1 tsp of cinnamon. Stir to combine and set aside.
Fold the egg whites into the egg yolk mixture. This may take a few minutes as the egg yolk mixture may be fairly thick.
Pour half of the egg mixture into the prepared loaf pan. Evenly top with the cinnamon and butter mixture. Then the remaining egg mixture, ensuring that the mixture has been spread to the edges of the pan.
Using a butter knife, make swirls into the bread, keeping the knife vertical to prevent too much mixing between the layers.
Bake for 30-40 minutes or until the top is golden.