Preheat the oven to 350°F (175°C) and line a 12-cup muffin tin with non-stick liners.
In a medium mixing bowl, whisk together the oat flour, protein powder, baking powder, and salt.
In a large mixing bowl, whisk the eggs, Greek yogurt, almond milk, maple syrup, and vanilla extract until a smooth emulsion is formed.
Fold the dry ingredients into the wet ingredients using a spatula until just incorporated; avoid over-mixing to maintain texture.
Gently fold in the fresh blueberries.
In a separate small bowl, combine the softened cream cheese and sweetener, whisking until smooth.
Fill each muffin cup halfway with the batter, then place 1 teaspoon of the cream cheese mixture in the center of each.
Distribute the remaining batter over the cream cheese centers to cover them completely.
Bake for 20-22 minutes, or until the tops are golden and a toothpick inserted into the cake portion comes out clean.
Allow the muffins to cool in the tin for 10 minutes before transferring to a wire rack for final cooling.