Anytime Birthday Cake

Anytime Birthday Cake

Happy Birthday! Give yourself the gift of a simple and easy festive cake that comes together in minutes. Each layer is cooked in the microwave for a perfectly spongy crumb. Now that's worth celebrating!

This recipe calls for a homemade buttercream that helps you build strong, sturdy layers. If you'd rather use store-bought (no judgements here!), whip the canned frosting with 1/2 cup powdered sugar to achieve the perfect consistency for building layer cakes.

All of Anyday’s recipes are tested (and retested!) in many different microwaves and home kitchens to make sure they work — and work well.

1-7" Cake

Select your microwave wattage in the dropdown. The cook times in this recipe will automatically change accordingly.

To find your microwave’s wattage, look at the front panel, the side of the door, in the back, in the user manual, or Google the model number. If both an input and output wattage are listed, use the output.

Wattage translates to how powerful the microwave is. The higher the wattage, the faster your food will cook. The lower the wattage, the longer the cook time.

When in doubt, start with less time — you can always add more.


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Product Size

  • Small Dish
  • Medium Shallow
  • Large Shallow
  • Medium Deep
  • Large Deep

Prep Time

5 mins

Cook Time

11-12 mins

Free Time

to decorate with streamers and balloons


For the cake

  • 1-15.25 ounce box vanilla sprinkle cake mix, plus ingredients called for on the back of the box

For the frosting

  • 1 cup unsalted butter (2 sticks), softened
  • 2½ cups powdered sugar, plus more as needed
  • ½ teaspoon salt
  • 1 teaspoon vanilla extract
  • Sprinkles, for decoration (optional)


  1. Lightly grease the Anyday dish with cooking spray and line the bottom with a cutout circle of parchment paper.
  2. In a separate bowl, prepare cake batter to package directions. 
  3. For 7” cake (Medium Deep or Medium Shallow): Pour half of the batter into the Anyday dish and cook in the microwave uncovered for 5-6 minutes for each cake, or until an inserted toothpick comes out clean. 
  4. Allow the cake to cool completely before unmolding and frosting, about 10-15 minutes. Repeat with remaining batter.
  5. While the cakes cool, prepare the frosting: In a bowl, whisk butter (or mix with a hand mixer) until light and fluffy. Add powdered sugar, salt, and vanilla and mix until a smooth and fluffy cream is formed, about 5 minutes. If the frosting is too soft, add more powdered sugar in ½ cup increments.
  6. Unmold each cake layer. Using a long, serrated knife, split each cake layer along its equator.
  7. Place one layer on a clean plate and gently spread an even layer of frosting on top. Repeat until all the layers are stacked. Cover sides and top with remaining frosting. Decorate with sprinkles, if desired.

Serving suggestions & tips

  • Don't want to make your own frosting? Use store-bought to save time! We reccomend whipping a can of frosting with 1/2 cup of powdered sugar to achieve the right texture to build this cake. The frosting should be smooth, spreadable, and stand up on its own on a spatula. If your frosting is still loose and sticky, add more powdered sugar.
  • For an extra-moist cake, brush each layer with simple syrup while hot. 
  • To make cake pops, crumble the cooked cake and mix with frosting until a malleable mixture is formed. Roll into golf size balls between your hands, allow to chill in the fridge for 10 minutes and coat in melted dipping chocolate. 
  • Make a trifle by layering pieces of cake with fresh fruit, frosting and whipped cream or pudding in the clean Anyday dish.