Banana Muffins

I baked this last Sun day and its good. Got the recipe from Joy of Baking but i do some changes instead of white chocolate I use the regular chocolate chips.

1 3/4 cups all-purpose flour
1/2 cup sugar
1/4 cup light brown sugar
1 teaspoons baking powder
1/2 teaspoon baking soda
1/4 teaspoon salt
1/4 cup chocolate chips or raisin
2 eggs, lightly beaten
1/2 cup unsalted butter, melted and cooled
1 1/2 cups ripe large bananas mashed
1 teaspoon pure vanilla extract
1 large banana, sliced (optional)

Preheat oven to 350 degrees F. Grease the muffin pan.
In a large bowl combine the flour, sugars, baking powder, baking soda, salt, and chocolate or raisin. Set aside.
In a medium-sized bowl combine the mashed bananas, eggs, melted butter, and vanilla. With a rubber spatula or wooden spoon, lightly fold the wet ingredients (banana mixture) into the dry ingredients until just combined and batter is thick and chunky. (The important thing is not to over mix the batter. You do not want it smooth. Over mixing the batter will yield tough, rubbery muffins.) Spoon the batter into the prepared muffin tins and place a slice of banana on top of each muffin. Bake about 20 - 25 minutes or until a toothpick inserted in the center comes out clean. Place on a wire rack to cool for five minutes and then remove muffins from pan. Serve warm or at room temperature.