For this project you will need a small heart-shaped cookie cutter, food coloring, and a recipe for two pound cakes, which will be baked separately in the same 5-by-9-inch loaf pan. Martha Stewart's Classic Pound Cake works perfectly for this project.
Step 1: Bake the first pound cake, dyed pink.
To start the hidden heart cake you will need to prepare and bake the first pound cake in a 5-by-9-inch loaf pan. You should dye the cake batter the color you will want your hidden heart inside to be (I used neon pink liquid food coloring).
Once the pound cake is baked, cooled, and removed from the pan, transfer it to the freezer for about 20 minutes. (It's much easier to cut a cold or semi-frozen cake.)
Step 2: Cut out the hidden hearts.
Use a serrated knife to cut the entire pound cake loaf into thick, 3/4-inch to 1-inch slices. Then use a heart-shaped cookie cutter to cut hearts from the center of each of the slices. Be gentle when handling the hearts, they will need to remain intact for the second cake.
Step 3: Prepare the second cake batter.
Prepare the batter for the second pound cake and set it aside. For the best results, you will want to use the same loaf pan you used for the first pound cake to bake the second. Be sure the pan is very clean and re-greased to prevent any sticking.
Step 4: Stack the hearts inside the loaf pan.
Place a very thin layer of batter on the bottom of the loaf pan. Then carefully stack the hearts upright, inside the pan, in a straight line. Gently press the bottom point of the hearts into the layer of batter on the bottom of the pan.
Step 5: Pour the remaining batter on top of the hearts.
Carefully pour the batter on the sides of the hearts and then on top of the hearts. Make sure they are completely covered with batter. Use a rubber spatula to smooth the top surface, then bake as indicated in the pound-cake instructions.
Be sure to check on the cake while it's baking. The total bake time will likely be about 10 to 15 minutes less than indicated since the hearts in the center are already baked.
To make sure your cake is fully baked, use the trusty old toothpick trick: insert a toothpick near the center (but in this case, closer to the sides). When the toothpick comes out clean, you are all set.
Step 5: Bake and cool the hidden heart cake before slicing.
Once the hidden heart cake is fully baked, transfer to a wire rack to cool in the pan for 30 minutes. Then remove the cake from the pan, and let it cool completely.
Slice and surprise! The pound cake can be served alone, or with fresh fruit and whipped cream. Either way, it is a lovely treat for such a loving day.