Preheat oven to 350°F. Butter and flour three 9-inch round cake pans or spray with baking spray. Set aside.
In a large mixing bowl, using an electric mixer, beat together, cake mix, flour, gelatin mix, buttermilk, oil and eggs. Beat on medium speed until fully combined.
Divide batter evenly between pans. Bake for 23-25 minutes or until a toothpick inserted into the center comes back clean. Cool in the pans for 20 minutes then remove and cool completely on a cooling rack.
To make frosting: In a large mixing bowl using an electric mixer, whip together cream cheese butter and vanilla for 2 minutes or until fluffy.
Lower the speed of the mixer and gradually add powdered sugar. Stop and scrape the sides of the bowl as needed. Add strawberries and food coloring, if using. Whip until fully combined. Add additional powdered sugar to stiffen frosting to your taste.
Frost between cake layers first, then top and sides. Decorate with whole strawberries. Chill for 6 hours or overnight to allow icing to set. (You may wait until just before serving to garnish with berries)
Slice and enjoy. Store leftovers chilled.