Preheat the oven: Set it to 350°F (175°C). Line a muffin tin with paper liners or grease well.
Soak the oats: Combine oats and milk in a bowl. Let them sit for 10 minutes to soften.
Prepare dry ingredients: Whisk flour, baking powder, baking soda, salt, and cinnamon in another bowl.
Mix wet ingredients: Stir melted butter, sugar, egg, and vanilla into the oat mixture until well combined.
Combine everything: Slowly fold the dry mix into the wet ingredients. Stir gently—overmixing leads to tough muffins.
Add chocolate chips: Stir them in, trying not to eat half the bag in the process.
Fill the muffin tin: Divide batter evenly, filling each cup about ¾ full.
Bake: Place in the oven for 18–20 minutes, or until a toothpick comes out with a few moist crumbs.
Cool & enjoy: Let them cool for 5 minutes before devouring. Good luck stopping at just one.