Preheat oven to 350°F (175°C) and grease or line a 12-cup muffin tin.
In a large mixing bowl, whisk together oat flour, protein powder, baking powder, baking soda, and salt.
In a medium bowl, blend Greek yogurt, eggs, almond milk, 1/3 cup sweetener, and vanilla extract.
Incorporate the wet ingredients into the dry ingredients, stirring until just combined.
Gently fold the blueberries into the muffin batter.
In a small bowl, mix the softened cream cheese with 2 tablespoons of sweetener until smooth.
Distribute half of the muffin batter into the tin, add a dollop of the cream cheese mixture to each center, and cover with the remaining batter.
Bake for 18 to 22 minutes until a toothpick inserted into the muffin edge comes out clean.
Allow muffins to cool in the pan for 10 minutes before transferring to a wire rack.