Heat oven to 400 degrees F. In a large mixing bowl, combine flour, sugar, salt, baking powder. Add chocolate chips.
In a small bowl, combine milk, vegetable oil, and egg and mix well. Add it to the dry mixture and mix until combined. Batter will be lumpy. Do not over-mix.
In a small bowl, combine 3 tbsp sugar and brown sugar for the muffin topping.
Spray mini muffin pan with cooking spray or line with cupcake liners. Fill each mini muffin cup 2/3 full. Sprinkle sugar mixture on top of each muffin. Bake at 400 degrees F for 9 - 10 minutes until golden brown or until toothpick inserted comes out clean. If baking regular sized muffins, bake for 20 -25 minutes.