Preheat oven to 400°F.
Combine the flour, oats, baking powder, baking soda, salt, and ground flax in a large bowl, stirring with a whisk. In a separate bowl, combine the honey, yogurt, milk, vanilla, and egg, stirring with the whisk. Add this liquid mixture to the dry mixture and stir just until moist. Fold in the blueberries. Spoon into muffin cups. (We use the silicone muffin cups but, otherwise, you may need to grease your pans first. If you are making this recipe dairy-free, you can use coconut oil to grease the pans.)
Bake for 15 minutes or until a toothpick inserted in the center of the muffin comes out clean. Cool in pans for about 10 minutes and remove to cool completely on a wire rack. Enjoy!