Preheat oven to 300 degrees F.
Separate the eggs and whip the whites and cream of tartar until very stiff (I use my beloved stand mixer and let it go for 5 minutes).
Slowly sift in the protein powder into the whites.
Combine softened cream cheese (OR YOLKS) and natural sweetener.
Using a spatula, very gently fold the cream cheese into the whites.
Spray a lasagna pan with coconut oil spray and spoon the mixture into the pan.
Bake for 18 to 20 minutes.
Remove from oven and let cool.
To make the CUSTARD: Whisk egg yolks, almond milk, and natural sweetener in medium metal bowl to blend.
Slowly mix in the melted butter so the eggs don't cook unevenly.
Set bowl over saucepan of simmering water.
Whisk mixture constantly and vigorously until thickened and instant-read thermometer inserted into mixture registers 140°F for 3 minutes, about 5 minutes total (or coats the back of a spoon).
Remove mixture from over water and chill for at least 1 hour in the fridge. (It can be prepared 1-3 days ahead and refrigerated. Re-whisk before serving.)
Place onto cooled bottom layer.