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Valentine's Day Mosaic Sheet Cake

Cook Time:
25 mins
Prep Time:
20 mins

Chef notes

I love this recipe because it's a quick way to make a delicious and showstopping cake for Valentine's Day. Bonus: It's two desserts in one — cake and cake truffles (made from the cake trimmings), the latter of which can be boxed up and gifted to your sweetheart or galentines.

Technique tips: Use foil as a divider in your sheet pan to keep the colors separate. Add an extra 1/4 cup all-purpose flour or box mix to make the cake more stable. Brush simple syrup on the warm cake rounds to keep them moist. When making a boxed cake, elevate the flavor and texture by using milk in place of water (or coffee if it's a chocolate cake) and melted butter in place of oil. I also like to add a small package of instant pudding and a splash of clear vanilla extract. Cover any leftover cut cake with a piece of plastic wrap to keep it from drying out.

Special equipment: 5-inch round cutter, cake turn table, 8-inch white cake drum, 14-inch piping bag and silicone heart truffle mold.


Mosaic Cake
  • 2 (15.25-ounces) boxed white cake mix, such as Pillsbury Classic White
  • 2 (3.4-ounce) boxes instant vanilla pudding
  • 1 cup unsalted butter, melted
  • cups whole milk, room temperature
  • simple syrup
  • frosting, homemade or store-bought
  • 1 (16-ounce) can vanilla frosting
  • 1 (16-ounce) can strawberry frosting
  • 1 (16-ounce) can dark chocolate frosting
  • sprinkles
  • pink sprinkles
Cake Truffles
  • leftover cake scraps
  • frosting, store-bought or homemade
  • dark chocolate, melted
  • sprinkles, for garnishing


For the mosaic cake:


Preheat oven to 350 F. Line a large baking sheet with parchment paper.


Measure and cut a piece of aluminum foil that's about 15-by-15-inches and fold it in half. Take the folded edge of the foil and fold in down into roughly 2-by-15-inch strips. Continue to fold the foil a couple more times and stop when you get about 4 inches from the bottom, unfolded edge of the foil. Take the pieces that are not folded and fold them out, as if you were making a paper plane. Place the foil divider on the parchment-lined sheet tray and make sure to keep it straight. Flatten down the edge of the foil, if needed, so cake batter doesn't spill underneath when you pour it into the pan. Place strips equal distance from each other, roughly 6 inches apart, to separate the pan in thirds. Now you should have 3 rectangles, roughly 6-by-12 inches. Spray pan with nonstick spray and set aside.


Prepare the cake mix according to instructions on the box, using milk in place of the water and melted butter in place of the oil. Add in the additional flour, pudding mix and vanilla extract. Using a hand mixer or whisk, stir for about 2 minutes on medium speed, until the batter is smooth.


Pour 1/3 of the vanilla batter into one of the empty rectangles in the pan.


Tint the remaining batter pink and pour half of what's left into the other empty rectangle.


Add red food coloring to the remaining pink batter, mix to combine and pour into the last open rectangle in the pan.


Bake for about 22 to 26 minutes, or until a toothpick inserted in the center of the cake comes out clean. Remove from oven and cool completely.

To decorate:

Carefully remove the 3 different cakes from the pan and gently remove the foil dividers. Stack the cakes into a large rectangle or cut two 5-inch circles from each. If using circles, cut the circles in half again and mix and match the colors and then reassemble them into new, two-toned rounds.

As you stack the cake rounds, brush a thin layer of simple syrup and pipe frosting between each layer. 

For the cake truffles:


Combine any remaining cake scraps with some frosting — just enough so that the cake scraps hold their shape when pressed together.


Pour a thin layer of melted chocolate into silicone truffle mold, coating the bottom and the sides. Let harden and then press a small amount of the cake mixture into the form. Top with additional melted chocolate and let harden.


Remove cake truffles from the silicone mold and decorate with additional melted chocolate and sprinkles.