In a medium bowl, whisk together the flour, sugar, baking powder, salt, and cinnamon.

In a large bowl, whisk together the eggs, buttermilk, oil, butter, and vanilla until well combined.

Add the dry ingredients into the wet ingredient mixture and use a spatula to fold together until just combined.

Fold in the chocolate chips and cover with a plate or towel.

Let the muffin batter rest for 15 minutes while the oven preheats to 425°F.

Line every other well of a muffin tin (6 total) and use an ice cream scoop to add generous portions of batter to each well. The batter should come to the top of each well!

Sprinkle on a few more chocolate chips over the top of each muffin, followed by the sanding sugar.

Bake for 5 minutes at 425°F before dropping the temperature to 350°F and baking for an additional 12-15 minutes.

Check for doneness by inserting a toothpick into the center of a muffin. If it comes out clean, they’re ready!

Cool in the pan before serving.