Deb’s favourite Banana Chocolate Chip Muffins

½ c. butter
½ c. sugar
1 egg
1 c. mashed banana
1½ c. flour
½ tsp. vanilla
½ tsp. nutmeg
1 tsp. baking powder
1 tsp baking soda
½ tsp. salt
½ c. chocolate chips
Cream butter and sugar. Add egg. Add the rest of the ingredients and mix well, chocolate chips last. Bake at 375° for 20-25 minutes.