Cupcakes with frosting, sprinkles, and cookies.

Funfetti Birthday Cake Cupcakes

08/31/2025 | Bonia Bakery |

Birthdays have always been a big deal in my family. Growing up, we didn’t need balloons or even a big fancy cake—what mattered most was that there were sprinkles involved. Sprinkles meant celebration. They meant joy, happiness, and that extra something that turned an ordinary day into a special one.

That’s why these Funfetti Birthday Cake Cupcakes are so close to my heart. They taste like childhood birthdays, sleepovers with friends, and the kind of happiness that only comes from biting into a soft, fluffy cupcake with colorful rainbow sprinkles baked right inside. And of course, no birthday treat would be complete without frosting piled high—and in this case, it’s a cookie-filled frosting that takes these cupcakes over the top.

If you’re looking for the perfect dessert to bring to a party, bake for a birthday, or honestly just make for yourself because Tuesdays deserve sprinkles too, these cupcakes are it. They’re fun, nostalgic, and guaranteed to make anyone smile.

Ingredients

Cupcakes (Makes 12)

  • 6 tbsp unsalted butter, room temperature
  • 6 tbsp avocado oil (or neutral oil)
  • 1 cup granulated sugar
  • 2 large eggs, room temperature
  • 1 tbsp vanilla extract
  • 1 ½ cups cake flour
  • ½ tsp salt
  • 1 ¼ tsp baking powder
  • ⅔ cup + 1 tbsp buttermilk
  • 3 tbsp rainbow sprinkles

Frosting

  • Filling from 8–10 Goodie Girl Birthday Cake sandwich cookies
  • ½ cup unsalted butter, room temperature
  • 2 ½ cups powdered sugar
  • ¼ tsp salt
  • 2 tbsp milk
  • ½ cup finely crushed birthday sandwich cookies (folded in for texture)

Topping

  • 1 Goodie Girl Birthday Cake sandwich cookie per cupcake
  • Extra rainbow sprinkles for decorating

Directions

Make the Cupcakes

  1. Preheat oven to 350°F (175°C) and line a 12-cup muffin tin with cupcake liners.
  2. In a large bowl, beat together the butter, avocado oil, and sugar until light and fluffy.
  3. Add the eggs one at a time, mixing well after each. Stir in the vanilla.
  4. In a separate bowl, whisk together the cake flour, salt, and baking powder.
  5. Add the dry ingredients to the wet ingredients in three parts, alternating with the buttermilk. Begin and end with the flour mixture, mixing until just combined.
  6. Gently fold in the rainbow sprinkles (don’t overmix or they’ll bleed into the batter).
  7. Divide the batter evenly between the cupcake liners, filling each about ⅔ full.
  8. Bake for 18–20 minutes, or until a toothpick inserted into the center comes out clean.
  9. Let cupcakes cool completely before frosting.

Make the Frosting

  1. In a large mixing bowl, beat the butter with the sandwich cookie filling until smooth and creamy.
  2. Add the powdered sugar, salt, and milk, and beat until light and fluffy.
  3. Gently fold in the crushed sandwich cookies for a little crunch and texture.

Decorate

  1. Pipe the frosting generously onto each cooled cupcake.
  2. Top each cupcake with a full sandwich cookie and a shower of rainbow sprinkles.