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Copycat Costco Sheet Cake

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A homemade version of the beloved Costco sheet cake, known for its rich, moist texture and sweet buttercream frosting—perfect for parties and celebrations.

Ingredients

Scale
  • 3 cups all-purpose flour
  • 2 ½ cups granulated sugar
  • 1 cup unsalted butter, softened
  • 1 cup whole milk
  • 1 cup sour cream
  • 4 large eggs
  • 2 ½ tsp baking powder
  • ½ tsp baking soda
  • 1 tsp salt
  • 1 tbsp vanilla extract
  • 1 tsp almond extract
  • For Frosting:
  • 1 ½ cups unsalted butter, softened
  • 5 cups powdered sugar
  • 2–3 tbsp heavy cream
  • 1 tbsp vanilla extract
  • Pinch of salt

Instructions

  1. Preheat oven to 350°F (175°C) and grease a 12×18 inch sheet cake pan.
  2. In a large bowl, cream together butter and sugar until light and fluffy.
  3. Beat in the eggs one at a time, then mix in the vanilla and almond extracts.
  4. In a separate bowl, combine flour, baking powder, baking soda, and salt.
  5. Gradually add the dry ingredients to the wet mixture, alternating with milk and sour cream. Mix until smooth.
  6. Pour batter into the prepared pan and spread evenly.
  7. Bake for 30–35 minutes or until a toothpick inserted in the center comes out clean. Let cool completely.
  8. For the frosting: Beat the butter until creamy, then gradually add powdered sugar, cream, vanilla, and salt. Beat until fluffy.
  9. Frost the cooled cake evenly with buttercream. Decorate as desired.

Notes

  • Ensure all ingredients are at room temperature for best mixing results.
  • You can use a piping bag for decorative frosting if replicating the Costco look.
  • Store cake in an airtight container at room temperature for up to 3 days.

Nutrition

Keywords: Costco sheet cake, copycat cake recipe, party cake, buttercream cake

Find it online: https://recipesfoodeasy.com/copycat-costco-sheet-cake/