Best Flag Sheet Cake: Tips and Tricks for a Perfect Patriotic Dessert

This Flag Sheet Cake recipe is an absolute hit at any patriotic celebration. It’s a fun and easy way to show off your patriotism this Fourth of July or Memorial Day.

It’s also super easy to make! Plus, who doesn’t love turning a simple cake into a stunning flag-inspired dessert?

flag cake made with fresh berries in pan

Flag Sheet Cake Recipe + Tips for Successs

A recipe for a flag cake sheet cake that isn't too huge. A moist and delicious vanilla cake with the perfect cream cheese frosting and plenty of fresh summer berries.
Prep Time 45 minutes
Cook Time 18 minutes
Total Time 1 hour 3 minutes
Serving Size 20 pieces

Ingredients 

  • ½ cup unsalted butter at room temperature (1 stick)
  • 1 ½ cups sugar
  • 3 eggs
  • ½ cup milk
  • 1 teaspoons pure vanilla extract
  • 1 ¾ cups flour
  • 1 tablespoon cornstarch
  • ½ teaspoon salt
  • ¼ teaspoon baking soda
  • ½ teaspoon baking powder

For the Cream Cheese Frosting

  • 1 cup unsalted butter at room temperature (2 sticks)
  • 12 ounces cream cheese (room temperature)
  • 3 ½ cups powdered sugar
  • 1 teaspoon vanilla extract

To assemble

  • 1 cup blueberries
  • 3 cups raspberries

Instructions 

Make the Cake

  • Prep. Start by preheating the oven to 350°F and greasing a 10×16-inch rimmed sheet pan with non-stick baking spray. 
  • Beat butter and sugar. In a large mixing bowl, beat the butter and sugar with an electric mixer on medium speed until light and fluffy. Add the eggs one by one, fully incorporating each egg before adding the next one, and stir in the vanilla.
  • Combine dry ingredients. Combine the flour, cornstarch, salt, baking soda, and baking powder in a separate bowl. Gradually add the dry ingredients to the butter mixture, alternating with the milk, starting and ending with the dry ingredients. Mix on low until everything is just combined. Don't forget to scrape down the sides of the bowl as needed.
  • Pour into baking sheet. Pour the batter into the pan and smooth the top with a spatula. Bake for 17-19 minutes or until a toothpick comes out clean. Let the cake cool completely in the pan on a wire rack.

Make the Frosting

  • Use a clean bowl to beat the butter, cream cheese, and vanilla until it becomes fluffy. Gradually add the powdered sugar, beating until the frosting becomes smooth.

Assemble the Cake

  • Spread. Spread half the frosting over the cooled cake. Using a toothpick, draw a rectangle for blueberries in the upper left corner, fill it with blueberries, and arrange double rows of raspberries across the cake, aligning with the bottom of the blueberry rectangle. 
  • Add the berries. Fill the upper left square with blueberries. Make a double row of raspberries on top of the cake to the right of the blue square. You will want the bottom of the blue square to line up with the bottom of a raspberry row, so space the rows accordingly. Continue with double rows of raspberries, leaving space in between for white stripes.
  • Add the remaining frosting. Finally, fill a piping bag fitted with a star tip with the remaining cream cheese frosting. Then pipe stars over the blueberries and stripes between the raspberry rows using the remaining frosting in a piping bag fitted with a star tip.
  • Serve. When it's time to serve, you can serve the cake directly from the pan and refrigerate any leftovers.

Notes

Before starting your baking, make sure to let your butter, eggs, and cream cheese reach room temperature to blend together smoothly, providing a better texture for both your cake and frosting.
Make sure to properly grease and flour your sheet pan instead of using parchment paper to prevent the cake from sticking, allowing it to easily come out of the pan while retaining its shape.
If you make any mistakes when arranging the berries or piping the frosting, don’t worry. The final outcome will still resemble a flag and look beautiful.
If you’re not fond of raspberries, you can replace them with halved strawberries.
Calories: 349kcal | Carbohydrates: 49g | Protein: 4g | Fat: 16g | Saturated Fat: 6g | Trans Fat: 1g | Cholesterol: 44mg | Sodium: 257mg | Potassium: 91mg | Fiber: 2g | Sugar: 38g | Vitamin A: 690IU | Vitamin C: 5mg | Calcium: 44mg | Iron: 1mg

More Tips:

Make sure to let your cake cool completely in the pan on a cooling rack before frosting it, as frosting a warm cake can cause the frosting to melt and become messy.

If your frosting is too thick to spread, add a teaspoon of milk to thin it until it becomes spreadable. If it’s too thin, add more powdered sugar to thicken it.

To create a neat berry design, arrange your berries in straight, tight lines, resembling the precise stripes of a flag.

If you’re new to piping, practice on a plate or parchment paper before starting on the cake to get a feel for the required pressure and speed to create neat stars and stripes.

Always use a clean and sharp knife to cut the cake, wiping it between each cut so the cake layers and design remain neat and beautiful on every plate.

finished flag sheet cake with raspberries for red strips, blueberries for stars and piped cream cheese frosting

Serving Suggestions

Serve your Flag Sheet Cake with lemonade, iced tea, coffee, fruit salad, or vanilla ice cream!

About the Ingredients

Here are some easy swaps you can make for the Flag Sheet Cake recipe:

  • Butter: You can use margarine or coconut oil for a dairy-free option.
  • Sugar: Use coconut sugar or a sugar-free sweetener in equal amounts instead of regular sugar.
  • Eggs: For a vegan alternative to eggs, use flax eggs (1 tablespoon ground flaxseed mixed with 3 tablespoons water per egg).
  • Milk: Use almond, soy, or oat milk instead of regular milk.
  • Cream Cheese: Try vegan cream cheese or mascarpone instead of regular cream cheese.
  • Flour: Use gluten-free all-purpose flour instead of regular flour if you need to.
marble surface with raspberries blueberries, butter, sugar, cream cheese, milk, and flour for cake

Remember that changing these ingredients may affect the texture and taste of the cake, but don’t be afraid to experiment to find what works for you.

Storage Instructions

Cover and store the cake in the refrigerator to keep it fresh for up to five days. Use an airtight container or wrap it tightly in plastic to prevent it from drying out.

If you plan to freeze an unfrosted cake, wrap it tightly in plastic and aluminum foil. This will keep the cake fresh for up to 3 months. Before frosting and decorating, thaw the cake overnight in the refrigerator.

It’s not recommended to freeze a frosted cake, especially if it has cream cheese frosting or fresh berries. Freezing could cause the frosting to become grainy and the berries to turn mushy when you thaw the cake later.

close up view of flag sheet cake

What’s a better way to celebrate our country’s independence than this Flag Sheet Cake? It’s not only beautiful to look at, but it’s also seriously simple to make, and the flavors come together beautifully.

You can also get your kids involved in making this recipe. Let them stir and decorate with the berries. I find that this makes eating it even more fun when they know they’ve had a hand in preparing it. So why not give it a try?

picture of smiling female

By Katie Shaw

Katie lives in Virginia with her husband, three daughters, a chocolate lab, and over thirty chickens. She loves creating simple tutorials for sourdough, bread, and soap. Her recipes, articles, and YouTube videos reach millions of people per year.

Leave a Reply

Your email address will not be published. Required fields are marked *

Recipe Rating




3 Comments

  1. This looks delicious, but I’m quite puzzled by your statement above:
    “vanilla: vanilla is necessary as it adds a density to all baked goods”
    I thought vanilla was used for flavour; how would it add density to a cake? And actually, why would you want a dense cake? I’m sure I’m misinterpreting what you’ve stated, so please help me to understand it. Thanks!

    1. I have to say I agree with your comment. I had the exact same reaction when I read the instruction about vanilla adding density to the cake. It doesn’t make any sense at all to me.