• Preheat the oven to 350°F.
• Lightly spray a 9x5-inch loaf pan and then line it with parchment paper, leaving an overhang on the sides for easy removal later.

Prepare the Red Cake

• Prepare the red pound cake batter by mixing 1 box of pound cake mix with the eggs, water and butter listed on the package until smooth.
• Add red food coloring gel in small amounts at a time until you get a vibrant red color.
• Pour the red batter into the prepared loaf pan and carefully smooth the top.

Bake the Red Cake

• Bake at 350°F for 45 to 55 minutes, until a cake tester or toothpick inserted in the center comes out clean.
• Remove the cake from the oven and let it cool completely in the pan for 15 minutes.
• Lift it out of the pan and let it cool completely on a wire rack.

Cut Out the Red Hearts

• Once it’s completely cooled, slice it into ½-inch to ¾-inch-thick slices.
• Carefully cut heart shapes from the center of each slice with a heart-shaped cookie cutter. You may be able to make 2 hearts from some slices, as they may be larger than some of the other slices.
• Place the hearts on a parchment-lined cookie sheet and place them in the refrigerator for 20 to 30 minutes to help them firm up.

Make the Vanilla Pound Cake

• Prepare the vanilla pound cake batter by mixing your other box of pound cake mix with the eggs, water and butter listed on the package.
• Lightly spray a clean 9x5-inch loaf pan, and then line it with parchment paper, leaving an overhang on the sides for easy removal later.

Assemble the Hidden Heart Cake

• Remove the chilled hearts from the refrigerator and arrange them in a straight, tight row down the center of the prepared loaf pan.
• Use a scrap piece of the loaf, if necessary, as a wedge to hold the hearts in place snugly if you don’t have enough hearts. This will help stabilize the hearts while you pipe or spoon the batter around them.
• Slowly pipe or spoon the prepared vanilla pound cake batter around and over the hearts, starting on the bottom and working upward, making sure the hearts are fully covered without shifting their position.

Bake the Assembled Heart Cake

• Bake in the oven at 350°F for 55 to 65 minutes, checking for doneness by inserting a cake tester or toothpick into the sides of the loaf and gently pressing the top to make sure it springs back.
• Tent the top loosely with foil during the last 15 minutes if it begins to brown too quickly.
• Let the pound cake cool in the pan for 15 minutes.
• Lift it out using the parchment and cool completely on a wire rack before glazing.

Make the Glaze

• Whisk together the powdered sugar, 2 Tablespoons whole milk and vanilla extract until thick and slightly pourable.
• Add up to 1 more Tablespoon of milk if needed to thin the glaze.

Decorate the Cake

• Drizzle the glaze generously over the cooled cake.
• Immediately decorate with Valentine’s sprinkles before the glaze sets.
• Slice carefully to reveal the cute heart design inside.