Warning: this is RICH! I baked it in a casserole dish without a crust but it would work fine with a crust as well. I recommend almond meal, butter and stevia or erythritol for a crust.
This is a small cake. For a full cheesecake, I would recommend you quadruple this recipe (so use 2 pkgs of cream cheese, 4 eggs, etc).
3 Tbsp Butter
6 Tbsp Cocoa Powder
4 oz Cream Cheese, softened (1/2 package)
4 Tbsp Erythritol, like Wholesome Sweeteners Organic Zero or Z-Sweet, powdered (I whiz mine up in the blender)
20-25 drops Liquid Stevia
1 tsp Vanilla
Preheat oven to 350* and spray a small oven-proof dish with cooking spray. (Mine is about 4" square.)
Melt butter and remove from heat. Stir in cocoa and cream cheese. Add erythritol one tablespoon at a time, mixing thoroughly as you add each one. Add liquid stevia and vanilla, mix well. Stir in egg and pour mixture into prepared dish. Bake about 20 minutes, then turn off the oven and leave the cheesecake in for about 30 more minutes. The center should be set but wiggle some if you jiggle the dish. Remove from oven and let cool, then refrigerate at least a couple of hours to set. Slice and serve.