Preheat oven to 350℉ Grease a standard 12-cup muffin pan with nonstick cooking spray. Then line it with paper liners.

Place the butter in a small skillet or pan. Heat over medium heat. Stir or swirl the pan occasionally. The butter will begin to foam. Move the foam with your spoon or spatula. Look for lightly brown specks at the bottom of the pan. You will begin to notice a nutty aroma from the butter. Remove from the heat when the butter is light brown.

Pour the browned butter into a small heat-proof bowl. Let cool for about 5-minutes.

While the butter cools, whisk together the flour, baking powder, and salt in a large bowl.

Add the brown sugar to the cooled brown butter. Mix to combine. Add the eggs and vanilla extract. Stir until thick and creamy. Pour the butter mixture and milk into the flour mixture. Stir until a batter forms. Add the chocolate chips. Stir to combine.

Spoon batter into the prepared muffin pan. Top with additional chocolate chips and granulated sugar.

Bake until brown and a toothpick inserted into the muffin comes out clean, about 22 minutes.

To store: cover cooled muffins and keep on the counter for about four days. Or freeze cooled muffins in a freezer container for up to three months.