Line a standard 12-cup muffin tin with muffin liners or generously grease.
Place blueberries in a medium bowl.
In another medium bowl whisk together flour, baking powder, baking soda, cinnamon and salt. Sprinkle 2 tablespoons of this dry mixture over blueberries and stir to coat. (This will help distribute the blueberries throughout the muffins instead of sinking to the bottom.) Set aside.
Stir oats into dry mixture.
In the bowl of a stand mixer, fitted with the paddle attachment, beat honey and butter on medium-high speed until fluffy, about 2 minutes. Add eggs and vanilla; mix just until combined. Add mashed bananas and milk; mix just until combined.
Mixing on low speed, add oat mixture to wet ingredients, scraping down sides with a spatula as needed. Remove bowl from stand and fold in blueberries.
Spoon batter into prepared muffin tins, filling muffin cups about 3/4 full. Bake 30 minutes, or until a knife inserted in the center comes out clean.
Cool muffins in tin on wire rack for 15 minutes. Remove individual muffins from pan and place back on rack to cool completely.
If using frozen blueberries, don't thaw them before tossing in the dry mixture and adding them to the batter. They'll hold their shape better this way.