Preheat oven to 375° F. Line 9 muffin tins with cups and spray with non-stick cooking spray.
Mix cream cheese, cinnamon, and lemon zest together in a small bowl. Cover and set in the fridge.
Combine the eggs, oil, and heavy cream into a medium or large bowl; whisk together until mixed well.
Add the vanilla protein powder, baking powder, and sweetener. Stir until just combined. Don’t over stir because protein powder can be temperamental.
Gently fold in the blueberries. Get out the cream cheese mixture from fridge. Spoon 1/2 the batter into the prepared muffin tins. Scoop about 2 tbsp of the cream cheese mixture into the center of each muffin. Fill prepared muffin with remaining batter.
Bake for 10 minutes or until no longer wet looking on top.
Delish! The cream cheese filling is sort of gooey yet cheesecakey.