In a small bowl, add the flour, baking powder and salt and chocolate chips and mix and set aside.
In a large bowl, add the egg and whisk in sugar.
Add the butter (be sure it is cooled and not hot) and mix into the egg and sugar.
Add sour cream and mix together well.
Pour the dry ingredients into the wet gradually and stir until incorporated.
Spray tin with nonstick cooking spray.
Fill the muffin tins to the top of the liners or top of the muffin tin.
Sprinkle on top of each muffin with the granulated/white sugar.
Bake for 30 minutes or until golden brown and the toothpick comes out clean.
Store in an airtight container or freeze extras.
Notes
We use milk chocolate chips, but you can use semi sweet as well.Add 1 to 2 Tablespoons of water if the mixture seems dry.Melted butter should be cooled, not hot or it will scramble the eggs.When making this recipe, I sometimes, add all the dry ingredients separate from all the wet and then combine them together. And sometimes when in a hurry, I don't. If you mix the wet ingredients together first, it is easier to incorporate and no lumps.