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Flag Cake

Flag Cake

A charmingly festive flag cake with a delicious buttercream frosting. This festive cake will be the centerpiece of all your red, white and blue holidays.
Course Dessert
Cuisine American
Keyword Flag Cake
Prep Time 45 minutes
Cook Time 30 minutes
Total Time 1 hour 15 minutes
Servings 15 slices
Calories 622kcal
Author Cathy



  • 1 box vanilla cake mix
  • 1 cup full fat sour cream
  • 1/2 cup whole milk
  • 1/3 cup butter, melted
  • 2 large eggs
  • red and blue food coloring

Buttercream Frosting:

  • 1 cup butter, room temperature
  • 1 cup shortening
  • 2 lbs confectioners sugar
  • 1-1/2 tbsps water
  • 1-1/2 tsps vanilla extract
  • red and blue food coloring
  • 1 tbsp red, white and blue sprinkles


  • Preheat oven to 350° F. Grease a 9 x 13-inch baking pan.
  • In a large mixing bowl, combine cake mix, sour cream, milk, butter, and eggs. Using a hand held or stand mixer, mix on high for 4 minutes.
  • Pour batter into your baking pan and spreading it out evenly.
  • Add drops of the blue food coloring to the top of the batter. Using the back of a spoon, swirl the food coloring into the batter until it begins to mix in. Repeat with drops of the red food coloring to the top while carefully swirling the red color around (make sure you don't over mix it, or you will end up with a purple cake).
  • Bake for 25-28 minutes until a toothpick can be inserted from the middle and comes out clean.
  • While cake is cooling, put together the buttercream. (The cake needs to be completely cooled down before frosting it.)
  • In a large mixing bowl, cream together butter and shortening at medium-high speed, until they are well combined. Turn speed down to low and slowly add in confectioners' sugar until incorporated.
  • Add water and vanilla and mix on high for 4-6 minutes, until light and fluffy.
  • Divide frosting into three separate bowls, coloring one batch red and another blue. Leave one white. Place your frosting into three piping bags with a large star tip.
  • Flip the cake onto a tray or you can leave it in the original baking pan.
  • To make the flag design, hold the piping bag straight up and down, gently squeeze the bag until there is a dot of frosting. Immediately stop the pressure on the bag and pull the bag straight up.
  • Start out piping the blue rectangle on the top left by adding four lines of the frosting dots about 5 inches long and 3inches wide.
  • Make the red and white strips starting out with the red line on top and alternating colors on each row going down to the bottom until the cake is completely covered.
  • Add sprinkles to the top of the cake.


See pictures within the post to help with decorating.


Calories: 622kcal | Carbohydrates: 80.6g | Protein: 3.4g | Fat: 31.3g | Saturated Fat: 14.3g | Polyunsaturated Fat: 6.5g | Monounsaturated Fat: 3.7g | Cholesterol: 39.6mg | Sodium: 263.9mg | Potassium: 32.8mg | Fiber: 0.5g | Sugar: 67.5g | Vitamin A: 16.4IU | Vitamin C: 0.2mg | Calcium: 11mg | Iron: 0.1mg