Preheat the oven to 425℉/218℃. Line your muffin tin with 12 liners and set aside. If you need a recommendation, this is my favourite tin.
In a medium-sized bowl, add in flour, oats, cinnamon, salt, cornstarch, baking powder, and baking soda. Using a spatula, mix until just completely combined.
In a large bowl add eggs, milk, vanilla, brown sugar, oil, and sour cream. Whisk until combined.
Add the dry into the wet and using a spatula, gently fold until a soft batter forms.
Mix in the mini chocolate chips until just combined. Do not over-mix!
Evenly divide the batter between 12 liners. Using a cookie scooper helps big time to minimize the mess. Sprinkle extra mini chocolate chips on top (optional).
Bake the muffins at 425℉/218℃ for 5 minutes and then 375°F for 14-18 minutes. The muffins are ready when a toothpick inserted comes out clean.
These muffins stay fresh covered at room temperature for up to 3 days, and in an airtight container in the refrigerator for up to a week!
