Preheat oven to 350°F (180°C) and prepare a muffin mold with muffin liners. Make sure you grease the liners to prevent the cupcakes from sticking.
Add cottage cheese to a high speed blender or food processor and blend until smooth.
In a large bowl, mash the banana then combine with blended cottage cheese, egg, maple syrup, vanilla extract and a pinch of salt. Stir well until you get a smooth mixture.
Add into the wet mixture oat flour, almond flour (or more oat flour/protein powder) and baking powder. Stir the ingredients together while pouring in the milk gradually. Start with 1 tablespoon and add slightly more if needed.
Wash the blueberries, then (optionally) add them to a bowl and toss them with ½ tablespoon of flour. Fold through the blueberries, being careful not to smash them.
Fill ⅔ of each muffin liner with the batter and bake in hot oven for 20 to 25 minutes. Make sure you do not overbake the muffins. They are ready when a toothpick inserted into the center comes out clean.
Remove your blueberry muffins from the oven and let cool over a baking rack for about 15 minutes.