Zucchini Carrot Apple Mini Muffins

Name: Zucchini Carrot Apple Mini Muffins
Ingredients: 1/2 cup all purpose flour; 1 1/2 cups whole wheat white flour; 1 1/2 teaspoons baking powder; 1/2 teaspoon baking soda; 1 teaspoon cinnamon; 1/4 teaspoon cardamom; 1/4 teaspoon nutmeg; 1/4 teaspoon salt; 1/4 cup brown sugar; 1/4 cup canola oil; 1 large egg; 1 large egg yolk; 1/2 teaspoon vanilla; 1/4 cup buttermilk; 1/2 cup finely grated zucchini, squeezed and drained; 1/2 cup finely grated carrot, squeezed and drained; 1/2 cup finely diced apple (approx 1 small apple); 1/2 cup quick oats; 2 tablespoons butter, softened