Whisk all the dry ingredients together very well. Set aside. Whisk together all the wet ingredients.Add the wet ingredients into the dry, then add the melted, cooled butter. Mix together until the batter is smooth.Use a 2 ounce ice cream scoop to evenly divide the batter into a muffin pan sprayed with cooking spray.Bake the muffins in a preheated 350 degree oven for 23-25 minutes. Remove from the oven and leave the muffins in the pan to cool for a few minutes before handling. Serve warm. Keep stored in an airtight container.