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Hidden Heart Chocolate Bundt Cake

02/03/2026 | Bonia Bakery |

This Hidden Heart Chocolate Bundt Cake proves you don’t need frosting, sprinkles, or extra embellishments to make a Valentine’s Day dessert feel special. On the outside, it’s a rich, classic chocolate bundt—simple, elegant, and unfussy. But once you slice into it, a bright pink heart is revealed right in the center of every slice, turning an already beautiful cake into something genuinely magical.

This is the kind of dessert that feels thoughtful without being overdone. The contrast between the deep chocolate cake and the strawberry heart is not only visually stunning, but perfectly balanced in flavor. It’s romantic, a little dramatic, and quietly impressive—ideal for Valentine’s Day when you want something that feels intentional but still approachable.

Why I Skipped the Frosting

I chose to leave this cake unfrosted on purpose. The chocolate cake is rich, moist, and flavorful on its own, and the strawberry heart adds just enough sweetness. In my opinion, too much sweetness can completely overpower a good dessert, and this cake really doesn’t need anything extra to shine.

That said, baking should always reflect your own taste. If you’d like to add a light dusting of powdered sugar, a simple chocolate glaze, or even a strawberry frosting, feel free. I personally love it just as it is—simple, elegant, and perfectly balanced.

About the Hidden Heart

The hearts are made using a boxed strawberry cake mix, which keeps things easy and reliable while still delivering great flavor and color. Baking the cake in a sheet pan allows you to cut out clean heart shapes that bake beautifully into the chocolate batter. I added a few drops of neon pink food coloring to make the hearts extra vibrant, but that step is completely optional.

Freezing the hearts before assembling the cake helps them stay in place and hold their shape while baking, so every slice reveals a clear, defined heart in the center.

Ingredients

Strawberry Heart Cake

  • 1 box strawberry cake mix
  • Ingredients listed on the box (eggs, oil, water, etc.)
  • A few drops neon pink food coloring (optional)

Chocolate Bundt Cake

  • 2 ½ cups all-purpose flour (300 g)
  • 1 ¼ cups unsweetened cocoa powder (125 g)
  • 1 tablespoon baking powder (12 g)
  • 2 teaspoons salt (12 g)
  • 2 cups granulated sugar (400 g)
  • ½ cup unsalted butter, room temperature (113 g)
  • ½ cup vegetable oil (120 g)
  • 3 large eggs, room temperature
  • 2 teaspoons vanilla extract (8 g)
  • 1 ½ cups buttermilk (360 g)

Directions

Make the Strawberry Heart Cake

  1. Preheat your oven to 350°F (175°C). Spray an 18×13-inch baking sheet with nonstick baking spray and line it with parchment paper.
  2. In a medium bowl, prepare the strawberry cake mix according to the package instructions. Add neon pink food coloring if using and mix until evenly combined.
  3. Pour the batter into the prepared baking sheet and smooth it into an even layer.
  4. Bake according to the package instructions, or until the cake is firm and a tester inserted into the center comes out clean.
  5. Let the cake cool in the pan for about 10 minutes, then carefully invert it onto a clean work surface to cool completely.
  6. Once fully cooled, use a heart-shaped cookie cutter to cut out as many hearts as possible.
    (Save the scraps for snacking or layering into parfaits.)
  7. Place the hearts on a baking sheet and freeze for 30 minutes, until firm.

Make the Chocolate Bundt Cake

  1. Keep your oven at 350°F (175°C). Generously spray a 12-cup bundt pan with nonstick baking spray or butter.
  2. In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.
  3. In a stand mixer fitted with the paddle attachment, beat the sugar, butter, and oil on medium speed for about 4 minutes, until light and fluffy.
  4. Beat in the eggs one at a time, mixing well after each addition. Add the vanilla extract and mix until combined.
  5. With the mixer on low speed, alternate adding the dry ingredients and the buttermilk—starting and ending with the dry ingredients (three additions of dry, two of buttermilk). Mix just until incorporated.
  6. Spoon one-third of the chocolate batter into the prepared bundt pan and smooth the top.
  7. Arrange the chilled heart cutouts upside down in a ring around the pan, with the pointed ends facing up (See photo below). Place them as close together as possible, leaving small gaps where needed to accommodate the curve of the pan.
  8. Carefully spoon or pipe the remaining batter over the hearts, filling in all gaps and smoothing the top.
  9. Bake for 55–65 minutes, or until the cake springs back when lightly pressed and a toothpick inserted into the center comes out clean.
  10. Let the cake cool in the pan for 10 minutes, then carefully invert onto a wire rack to cool completely.

Slice and enjoy the hidden surprise inside.

Bake Ahead & Storage

Bake Ahead:

  • The strawberry heart cake can be baked, cut, and frozen up to 2 days in advance. Keep the heart cutouts well wrapped or stored in an airtight container in the freezer until ready to use.
  • The fully baked bundt cake can be made 1 day ahead and stored at room temperature.

Storage:

  • Store the unfrosted cake tightly covered at room temperature for up to 3 days.
  • For longer storage, wrap slices individually and refrigerate for up to 5 days, or freeze for up to 2 months.
  • Bring refrigerated or frozen slices to room temperature before serving for the best texture and flavor.