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Kid-Approved Birthday Sheet Cake with Rainbow Sprinkle Buttercream

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A quick and easy birthday sheet cake with a tender crumb and rainbow sprinkle buttercream, perfect for celebrations without the stress. This forgiving recipe uses simple ingredients and comes together in under 15 minutes of active time.

Ingredients

Scale
  • 2 ½ cups (310g) all-purpose flour
  • 2 ½ teaspoons baking powder
  • ½ teaspoon baking soda
  • ½ teaspoon salt
  • ¾ cup (170g) unsalted butter, softened
  • 1 ¾ cups (350g) granulated sugar
  • 3 large eggs, room temperature
  • 2 teaspoons vanilla extract
  • 1 ½ cups (360ml) buttermilk, room temperature
  • ⅓ cup (80ml) neutral oil (canola or vegetable)
  • 1 cup (226g) unsalted butter, softened (for buttercream)
  • 4 cups (480g) powdered sugar, sifted
  • 2 tablespoons heavy cream (or whole milk)
  • 2 teaspoons vanilla extract (for buttercream)
  • ¼ teaspoon salt (for buttercream)
  • ½ cup (80g) rainbow sprinkles (jimmies style)
  • Extra rainbow sprinkles for decoration

Instructions

  1. Preheat oven to 350°F (175°C). Grease a 9×13-inch pan and line the bottom with parchment paper.
  2. In a medium bowl, whisk together flour, baking powder, baking soda, and salt.
  3. In a large bowl, beat softened butter and granulated sugar until light and fluffy, about 3-4 minutes.
  4. Beat in eggs one at a time, then add vanilla extract. Scrape down sides as needed.
  5. With mixer on low, add dry ingredients in thirds, alternating with buttermilk, beginning and ending with dry ingredients. Mix just until combined.
  6. Fold in oil with a rubber spatula until just incorporated.
  7. Pour batter into prepared pan and spread evenly. Tap pan gently on counter to release air bubbles.
  8. Bake for 28-32 minutes, until a toothpick inserted in center comes out clean or with a few moist crumbs. Cool in pan for 10 minutes, then turn out onto a cooling rack to cool completely.
  9. For buttercream: Beat softened butter until creamy, about 2 minutes. Gradually add sifted powdered sugar, one cup at a time, beating on low. Add heavy cream, vanilla, and salt. Beat on medium-high for 3-4 minutes until light and fluffy. Fold in rainbow sprinkles by hand.
  10. Once cake is completely cool, spread buttercream evenly over top. Sprinkle extra rainbow sprinkles on top. Slice and serve.

Notes

Room temperature ingredients are crucial for best texture. If you forgot to bring eggs to room temperature, place them in warm water for 5 minutes. Buttermilk can be microwaved for 10 seconds. Do not overmix batter. For clean slices, chill cake for 20 minutes before cutting and wipe knife between cuts. Cake can be stored at room temperature for up to 3 days or refrigerated for up to 5 days. Unfrosted cake can be frozen for up to 3 months.

Nutrition

Keywords: birthday cake, sheet cake, rainbow sprinkle, buttercream, easy cake, kid-friendly, celebration cake

Find it online: https://willarecipes.com/kid-approved-birthday-sheet-cake-with-rainbow-sprinkle-buttercream/