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Cozy Birthday Sheet Cake with Rainbow Sprinkle Buttercream

cozy birthday sheet cake with rainbow sprinkle buttercream - featured image
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A soft, buttery sheet cake with a tender crumb, topped with a creamy rainbow sprinkle buttercream. Perfect for celebrations or any day that needs brightening.

Ingredients

Scale
  • 2 ½ cups (315g) all-purpose flour
  • 1 ¾ cups (350g) granulated sugar
  • 2 ½ teaspoons baking powder
  • ½ teaspoon baking soda
  • 1 teaspoon salt
  • ¾ cup (170g) unsalted butter, softened to room temperature
  • ¼ cup (60ml) vegetable oil
  • 3 large eggs, room temperature
  • 2 teaspoons vanilla extract
  • 1 cup (240ml) buttermilk, room temperature
  • 1 ½ cups (340g) unsalted butter, softened to room temperature (for buttercream)
  • 4 cups (480g) powdered sugar, sifted
  • 2 teaspoons vanilla extract (for buttercream)
  • 3–4 tablespoons (45-60ml) heavy cream
  • ¼ teaspoon salt (for buttercream)
  • ½ cup (80g) rainbow sprinkles (jimmies-style), plus more for topping

Instructions

  1. Preheat oven to 350°F (175°C). Grease a 13×9-inch baking pan and line with parchment paper, leaving overhang on the long sides.
  2. In a medium bowl, whisk together flour, sugar, baking powder, baking soda, and salt.
  3. In a large mixing bowl, beat softened butter and vegetable oil on medium speed until smooth and creamy, about 2 minutes.
  4. Gradually add the dry ingredients to the butter mixture on low speed, mixing until just combined (mixture will look crumbly).
  5. Add eggs one at a time, mixing on low after each addition. Add vanilla extract and mix briefly.
  6. With mixer on low, add buttermilk in three additions, mixing until just combined after each. Stop mixing as soon as flour disappears.
  7. Fold batter gently with a rubber spatula to ensure even incorporation. Batter should be thick, smooth, and slightly glossy.
  8. Pour batter into prepared pan and spread evenly. Tap pan gently on counter 2-3 times to release air bubbles.
  9. Bake for 28-32 minutes, until a toothpick inserted in center comes out clean or with a few moist crumbs. Cool in pan on a rack for 15 minutes, then lift out and cool completely (about 1 hour).
  10. For buttercream: Beat softened butter on medium speed until smooth and creamy, about 3 minutes.
  11. Reduce speed to low and gradually add sifted powdered sugar, about 1 cup at a time, mixing until combined.
  12. Add vanilla extract, salt, and 3 tablespoons heavy cream. Beat on medium-high speed for 3-4 minutes until light and fluffy. Add more cream if needed for spreadable consistency.
  13. Gently fold in ½ cup rainbow sprinkles until just combined.
  14. Once cake is completely cool, spread buttercream evenly over top using an offset spatula. Top with additional sprinkles.

Notes

Room temperature ingredients are crucial. Do not overmix the batter. Use jimmies-style sprinkles to prevent color bleeding. Cool cake completely before frosting.

Nutrition

Keywords: birthday cake, sheet cake, rainbow sprinkle buttercream, easy cake recipe, celebration cake

Find it online: https://lolaspoon.com/cozy-birthday-sheet-cake-with-rainbow-sprinkle-buttercream-easy-recipe/