Prep your pan and oven: Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with liners or grease well.

Make oat flour if needed: Blend rolled oats in a blender until fine and powdery. Measure 1 cup of oat flour after blending so your amounts are accurate.

Whisk the dry ingredients: In a large bowl, combine 1 cup oat flour, 1 cup almond flour, 1/2 cup vanilla whey protein powder, 1 1/2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon fine sea salt, and 1 teaspoon cinnamon. Stir until evenly mixed.

Mix the wet ingredients: In a separate bowl, whisk 3/4 cup plain Greek yogurt, 2 large eggs, 1/4 cup olive oil, 1/3 cup maple syrup, 1 teaspoon vanilla extract, and 1/3 cup milk until smooth.

Combine gently: Pour the wet mixture into the dry mixture. Stir with a spatula just until you no longer see dry streaks. The batter will be thick but scoopable. If it seems too thick, add 1–2 tablespoons more milk.

Add blueberries: Fold in 1 to 1 1/4 cups blueberries. If using frozen berries, add them straight from the freezer and toss lightly with 1 teaspoon oat flour first to help prevent color bleeding.

Optional lemon zest: Fold in 1 teaspoon finely grated lemon zest for a bright, fresh note.

Fill the muffin cups: Divide the batter evenly among the 12 cups. For a bakery look, add 2–3 extra blueberries on top of each and a tiny pinch of coarse sugar.

Bake: Bake for 16–20 minutes, until the tops are set and lightly golden and a toothpick comes out clean or with a few moist crumbs. Start checking at 16 minutes.

Cool: Let muffins cool in the pan for 5 minutes, then transfer to a rack to finish cooling. This helps them set and keeps the bottoms from getting damp.