Prep the pan and oven: Heat the oven to 375°F (190°C). Line a 12-cup muffin tin with paper liners or lightly grease each cup.

Mix dry ingredients: In a large bowl, whisk the rolled oats, oat flour, whole wheat flour, baking powder, baking soda, salt, and cinnamon until evenly combined.

Combine wet ingredients: In a separate bowl or large measuring cup, whisk the eggs, Greek yogurt, applesauce, maple syrup, oil, and vanilla until smooth.

Bring the batter together: Pour the wet mixture into the dry ingredients. Stir gently with a spatula until just combined. The batter will be thick; avoid overmixing.

Fold in blueberries: Toss blueberries with a teaspoon of flour if using fresh (helps prevent sinking). Gently fold into the batter until evenly distributed.

Portion the batter: Divide the batter among the muffin cups, filling them almost to the top. Sprinkle the tops with the extra oats and, if using, a light dusting of turbinado sugar.

Bake: Bake for 16–20 minutes, or until the tops are set and golden and a toothpick inserted in the center comes out clean or with moist crumbs.

Cool: Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to finish cooling. This helps keep the bottoms from steaming and getting soggy.

Serve: Enjoy warm or at room temperature. For extra brightness, add a little lemon zest to the batter or a squeeze of lemon over warm muffins.