Preheat oven to 350 degrees Fahrenheit and spray a loaf pan with cooking spray.
Prepare your first pound cake following the box directions. Add the red food coloring to get a good pink color in the batter.
Pour the batter into the prepared pan and bake for 45 minutes (about 10 less than box directions).
Let cool on a rack for about an hour.
Remove the cake from the pan and refrigerate for several hours.
Slice the cold cake into slices no thicker than your heart shaped cookie cutter.
Use the cookie cutter to cut heart shapes from each slice and stack to the side.
Prepare the other box of pound cake mix following the box directions.
Spray loaf pan with cooking spray.
Pour 1/4" of the batter in the bottom of the loaf pan.
Place your heart cut-outs down the middle, keeping them straight and together.
Pour the remaining batter over the heart cut-outs in the pan. Ensure it gets down the sides and covers the top. (There will be a lot of batter left!)
Bake according to box directions.
Let cool on a rack for an hour.
Remove from pan and place on a platter.
In a medium bowl, add powdered sugar and slowly add milk. Whisk together until desired consistency is reached.
Drizzle icing over cake and serve.