Preheat oven to 400 degrees F. Line the bottom of a 9-inch springform pan with baking paper. Spray just a bit with non-stick cooking spray.
Separate the eggs. Beat egg whites with salt, half of the sugar substitute and half of the lemon juice, until stiff. Beat the egg yolks with the remaining sugar substitute until thick.
With the mixer on a low-medium setting, beat in the vanilla, cheese, lemon juice and rind, and protein powder until incorporated. Gently fold into the beaten egg whites.
Bake for 10 minutes at 400 degrees F; then turn the oven down to 300 degrees F and bake for another 40 minutes. When the top of the cake is set, turn off the oven and keep the oven door closed. Allow to cool for another hour in the oven. Remove and continue to cool on a wire rack.
Combine topping ingredients. Spread on top of the cheesecake and bake for 5 minutes at 450 degrees F.