Preheat the oven to 350 degrees.
Spray cooking oil in muffin tin or line with cupcake liners.
In a large bowl, mix together the flour, sugar, baking powder, baking soda, and salt.
In another large bowl or stand mixer, combine the egg, sour cream, melted butter, and vanilla extract, mixing well.
Gradually add the dry ingredients to the wet ingredients and stir with a spatula until just combined.
Stir in the chocolate chips until thoroughly combined.
Evenly divide the batter among the muffin tin until they are about 3/4-full.
Bake at 350 degrees for about 14-18 minutes. Start with 14 and keep an eye on them until the tops are golden brown. The muffins are done when a toothpick inserted into the center of the muffins comes out clean.