Preheat the oven to 375 and line a muffin pan with cupcake liners or spray with non-stick cooking spray.

In a medium bowl, whisk flour, baking powder, baking soda and salt together. Set aside.

In a large bowl, mix melted butter, sugar, sour cream, and egg together until combined.

Stir in flour mixture and then fold in chocolate chips.

Spoon muffin batter into the prepared muffin pan and sprinkle coarse sugar on each muffin.

Bake for 20 minutes until a toothpick inserted in the center comes out clean and the tops are golden.

Carefully remove from the oven and let sit for a couple minutes then transfer to a baking rack to cool.