Pre-heat the oven to 425℉ and line the muffin tin with cupcake liners.
In a medium mixing bowl, whisk together the melted butter, sugar, light brown sugar, and vegetable oil until combined.
Mix in the vanilla extract.
Next, add one egg at a time and whisking until combined with each egg addition.
In a separate mixing bowl, add the gluten free flour, salt, baking powder, and cinnamon. Whisk together until all the dry ingredients are evenly distributed.
Next, using a rubber spatula, fold in half of the flour mixture into the batter just until the flour is almost completely mixed in, some streaks of flour should remain.
Next, fold in all of the sour cream until the sour cream is almost completely mixed in.
Finally, add the last half of the flour mixture to the batter and gentle fold in just until the flour is almost mixed in. Then add the mini chocolate chips and gently fold in just until they are evenly distributed throughout the batter. DO NOT OVERMIX!
Let the batter rest for 30 minutes in the bowl before scooping.
After the batter has rested, using a cookie scoop, gently scoop the muffin batter into the pan so that each muffin is completely full.
Sprinkle some extra mini chocolate chips on top of the muffins before placing in the oven.
Place the muffins in the oven and bake at 425℉ for 5 minutes.
Once the muffins have been in the oven for the first 5 minutes, lower the oven temperature to 350℉ and DO NOT open the oven door.
Bake at 350℉ for another 20-25 minutes until the muffins are slightly golden brown, or a toothpick test comes out clean.
Let the muffins cool for 5-10 minutes before removing from muffin tin. Once removed from the muffin tin allow them to cool completely on a cooling rack before storing in an airtight container.