Chocolate Chip Muffin Tops

My family devoured them in just minutes.
Ingredients:
2.5 cups Bisquick or any muffin mix
1/2 cup sugar
1 egg
3/4 cups milk
1/2 stick melted butter
1 cup chocolate chips (I used dark chocolate)
Topping:
4 tbsp sugar
1 tbsp flour
2 tbsp butter (soft)
Preparation:
Grease backing sheet with cooking spray or butter.
Back 400 F. 15 min or or until slightly golden on bottom