Preheat oven to 400°F and grease a muffin tin or line with cupcake liners (I love parchment liners for easy cleanup).
In a medium bowl, combine the oats, flour, baking soda, baking powder, cinnamon, and salt. Set aside.
In a separate bowl, mix the oil, sugar, brown sugar, milk, vanilla, and egg until well combined.
Combine the wet and dry ingredients gently by hand — no electric mixer needed. Over mixing can make the muffins dense.
Fold in the blueberries carefully to avoid smashing them.
Pour the batter evenly into your prepared muffin tin, filling each cup about ¾ full (a cookie scoop works perfectly for this).
Bake at 400°F for 18–22 minutes, or until the tops are golden brown.