Spray a 9x13-inch baking pan with nonstick spray. Preheat oven to 350º if using a metal pan or 325º if using a glass pan.
In a medium bowl whisk together the flour, baking powder, baking soda and salt.
In a large mixing bowl mix the butter and brown sugar on medium speed until smooth and creamy. Reduce the mixer speed to low and beat in the eggs one at a time mix until well blended. Mix in the vanilla.
Add the dry ingredients and mix just until blended. Stir in the oats, chocolate chips, coconut and cherries. Spread the batter in the prepared pan and sprinkle M&Ms on top.
Bake until a toothpick inserted in the center comes out clean, 30 to 35 minutes. (Don’t overcook.) Cool on a rack to room temperature before cutting. Optional: Cut bars on the diagonal to form diamonds.