Combine milk and oats. Set aside for 20 minutes so the oats puff up and soak up some moisture. This is crucial to the recipe! (I usually melt the butter now so it has a few minutes to cool.) Don’t do this the night before as that’s too long for soaking. If you find the oats haven’t soaked up any moisture after 20 minutes, give it a stir and wait 10 more minutes.

Preheat oven to 425°F (218°C). Spray a 12-count muffin pan with nonstick spray or use cupcake liners.

Whisk the flour, baking powder, baking soda, cinnamon, and salt together in a large bowl until combined. Set aside. Whisk the melted butter, honey, egg, and vanilla extract together in a medium bowl until combined. Pour the wet ingredients into the dry ingredients, stir a few times, then add the soaked oats (milk included, do not drain) and blueberries. Fold everything together gently just until combined.

Spoon the batter into liners, filling them all the way to the top. Top with oats and a light sprinkle of coconut sugar, if desired. Bake for 5 minutes at 425 then, keeping the muffins in the oven, reduce the oven temperature to 350°F (177°C). Bake for an additional 16-17 minutes or until a toothpick inserted in the center comes out clean. The total time these muffins take in the oven is about 22-23 minutes, give or take. (For mini muffins, bake 11-13 minutes at 350°F (177°C).) Allow the muffins to cool for 5 minutes in the muffin pan, then transfer to a wire rack to continue cooling.

Muffins stay fresh covered at room temperature for a few days, then transfer to the fridge for up to 1 week.