Gluten-Free Banana Muffins

Name: Gluten-Free Banana Muffins
Cuisine: American
Ingredients: 2 cups Bob's Red Mill 1:1 Gluten-Free Baking Flour ((9 ounces/ 260 grams)); 1 teaspoon baking powder; 1 teaspoon baking soda; 1/2 teaspoon salt; 3/4 cup lightly packed dark brown sugar ((5 1/2 ounces/ 155 grams)); 3 medium very ripe bananas ((about 15 ounces/ 425 grams)); 2 large eggs, whisked ((about 4 ounces; 113 grams)); 1/2 cup oil or (1 stick) butter, melted and slightly cooled ((4 ounces; 113 grams)); 1/2 cup mini chocolate chips, optional ((3 ounces; 85 grams)); 1/2 cup chopped walnuts, optional ((3 ounces, 85 grams))