Preheat oven to 400F. Grease or line 16 muffin tin cups. Set aside.
In a large bowl, whisk egg, buttermilk, oil, and orange juice together until well-combined.
Add flours, brown sugar, baking powder, baking soda, salt, and 1/2 cup granola until combined.
Gently fold in the blueberries.
Divide the batter between the prepared muffin tin cups.
Sprinkle remaining 1/2 cup granola over the top of the batter.
Bake for 12-16 minutes, or until a wooden toothpick inserted in the center comes out clean. It's ok if there's some blueberry on it, but you don't want batter on the toothpick.
Let the muffins cool in the pan for 5 minutes before removing to a wire rack to finish cooling.
Buttermilk: Regular or low-fat buttermilk will work. If you don't have buttermilk, you can make a substitute with this recipe.
Oil: You can use a similar neutral oil, like canola oil.
Flours: Be sure to properly measure the flour to avoid heavy or dry muffins. To properly measure, either weigh the ingredients or sift/stir to break the flours up, lightly spoon into the measuring cup, and level.
Brown sugar: I use light brown sugar in this recipe, but you can use either.
Granola: I recommend using a plain granola that doesn't have nuts or fruit in it. Also, if you're using a sweet granola, keep an eye on it as it bakes so that it doesn't overbrown.
Blueberries: You can substitute an equal amount of frozen blueberries. Do not thaw before using.