Step 1

Preheat the oven at 350°F. Grease a loaf pan with butter and line with parchment paper.

Step 2

Make the red velvet cake batter according to the package directions. Pour the batter into the prepared pan. Bake for 20-25 minutes or until a toothpick or cake tester comes out clean.

Step 3

Remove the cake from oven and allow to cool in the pan for 5 minutes before unmolding onto a wire rack to cool completely.

Step 4

Cut the cake widthwise into 1-inch thick slabs. Place the slab on a work surface and use a 2-inch heart-shaped cookie cutter to make heart-shaped cutouts (see note). Place them in a resealable plastic bag and freeze for 30 minutes.

Step 5

Meanwhile, prepare the white cake batter according to the package directions. Clean and dry the loaf pan, greasing it and lining with parchment again.

Step 6

Pour a 1/2 inch layer of white cake batter into the bottom of the pan. Carefully stack the hearts upright in the pan side-to-side so they are touching. Then pour the remaining batter on top just to cover completely (you may find it helpful to have a second set of hands to pour while you hold the hearts while you're doing this).

Step 7

Bake 20-25 minutes or until a toothpick or cake tester comes out clean. Cool completely in the pan without unmolding.

Step 8

When completely cool, use a spatula to spread the frosting evenly across the top and sides of the cake. Add sprinkles and serve.