Preheat oven to 350°F (175°C). Generously grease a standard 12-cup muffin tin with non-stick spray or line with silicone/parchment liners.

Add rolled oats to a high-speed blender or food processor. Blend on high for 30-60 seconds until a fine oat flour forms.

In a large bowl, whisk together the oat flour, protein powder, baking powder, cinnamon, and salt.

In a medium bowl, whisk the eggs. Then add the Greek yogurt, milk, maple syrup, vanilla, and melted coconut oil. Whisk until completely smooth.

Pour the wet ingredients into the dry ingredients. Gently fold together with a spatula until just combined. Do not overmix.

Divide the batter evenly among the prepared muffin cups, filling each about ¾ full.

Bake for 18-22 minutes, or until the tops are golden and spring back when lightly touched, and a toothpick inserted comes out clean.

Let cool in the tin for 5 minutes, then transfer to a wire rack to cool completely before storing.