Prepare the pink cake: Preheat the oven to 350 degrees. In a medium bowl, cream the butter with an electric mixer, then add the powdered sugar and beat until fluffy. Add two of the eggs, beat until smooth, and then add the two remaining eggs, vanilla, and beet juice and beat until smooth.

In a separate bowl, combine the flour, salt, and baking powder. Add the dry ingredients gradually to the butter mixture and beat until evenly mixed. Pour the batter into a greased 9x5x3 loaf pan. Bake for 50 minutes (insert toothpick in the center to test; cake is done when toothpick comes out clean). Let cake cook for 10 minutes, then remove from loaf pan. Set aside.

Prepare the chocolate cake: In a medium bowl, cream the butter with an electric mixer, then add the powdered sugar and beat until fluffy. Add two of the eggs, beat until smooth, and then add the two remaining eggs and vanilla and beat until smooth. In a separate bowl, combine the flour, cocoa, salt, and baking powder. Add the dry ingredients gradually to the butter mixture and beat until evenly mixed. Set batter aside.

Prepare the pink hearts: Slice the pink cake into 3/4-inch-wide slices. Using a small heart-shaped cookie cutter, cut a heart-shaped piece out of each slice. Stack up all of the hearts.

Prepare the cake: Pour about 1 inch of chocolate cake batter into the bottom of a greased 9x5x3 loaf pan. Gently place the stack of hearts into the pan, making sure that there are no spaces between the heart shapes. Pour the remaining batter around the sides of the hearts and on top of the hearts, covering them completely. Bake the cake at 350 degrees for 50 minutes, or until a toothpick tester comes out clean. Let cake cool for 10 minutes before removing from pan. Frost the cake and serve in slices.