Preheat oven to 350°F and prepare two 9-inch round cake pans with grease and parchment.Whisk dry ingredients together in a large bowl.Add eggs, milk, oil, and vanilla, then mix until smooth.Slowly pour in hot water or coffee while mixing on low speed.Divide batter evenly into pans and bake for 30 to 35 minutes.Cool cakes completely before frosting and decorating with M&Ms.