If you are looking to create an elegant, rich, and show-stopping chocolate dessert, this Loaded Black Forest Slab Cake is the absolute pinnacle of indulgence. Moving away from standard round cakes, this sleek rectangular slab features layers of intensely moist dark chocolate sponge sandwiched tightly around a velvety, dense dark chocolate ganache filling packed with glossy glazed cherries.
Crowned beautifully with two parallel rows of piped chocolate whipped cream, delicate dark chocolate shavings, and a uniform line of vibrant ruby-red glacé cherries, this cake offers an incredible harmony of textures. Every slice cuts like a dream and delivers a gorgeous, professional pastry-shop presentation!
Prep time, Cook time, & Servings
- Prep Time: 45 minutes
- Cook Time: 25 minutes
- Total Time: 1 hour 10 minutes
- Servings: 12-14 clean rectangular slices
Ingredients
The Moist Dark Chocolate Sponge:
- All-Purpose Flour: 1.75 cups
- Granulated Sugar: 2 cups
- Unsweetened Cocoa Powder: 3/4 cup (high-quality Dutch-processed recommended)
- Baking Powder & Baking Soda: 1.5 tsp each
- Salt: 1 tsp
- Eggs: 2 large eggs (room temperature)
- Whole Milk: 1 cup
- Vegetable Oil: 1/2 cup
- Pure Vanilla Extract: 2 tsp
- Boiling Water or Hot Coffee: 1 cup (hot coffee intensifies the rich chocolate crumb)
The Dense Chocolate Ganache & Cherry Core:
- Dark Chocolate Chips or Coarsely Chopped Bars: 12 oz (60% to 70% cacao)
- Heavy Whipping Cream: 1 cup (hot, for the ganache)
- Maraschino or Glacé Cherries: 1 jar (16 oz), thoroughly drained and patted dry (divided for internal stuffing and top garnish)
- Cherry Kirsch or Syrup: 3 tbsp (optional, for brushing over the sponge)
The Light Chocolate Cream & Toppings:
- Heavy Whipping Cream: 1.5 cups (ice-cold)
- Powdered Sugar: 1/3 cup
- Cocoar Powder: 2 tbsp
- Dark Chocolate Block: For shaving into delicate curls
Step-by-Step Instructions
1. Bake the Chocolate Slab Base
- Preheat your oven to 350°F (175°C). Grease a large rectangular 9×13-inch baking pan and line the bottom with parchment paper.
- Dry Mix: Whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt in a large bowl.
- Wet Mix: Add the eggs, milk, vegetable oil, and vanilla extract. Beat on medium speed with a hand mixer for 2 minutes until smooth. Slowly fold in the boiling water or hot coffee by hand using a spatula. The batter will be extremely thin and watery—this is exactly what makes the sponge incredibly moist!
- Bake: Pour the batter into your pan and bake for 22 to 25 minutes until a toothpick inserted into the center comes out clean. Let it cool completely, then carefully slice the cake horizontally into two flat, equal-sized rectangular layers.
2. Whip the Thick Ganache Filling
- Melt: Place your dark chocolate chips or chopped chunks into a heatproof bowl. Pour 1 cup of hot, steaming heavy cream directly over the chocolate. Let it sit untouched for 5 minutes, then whisk smoothly until it forms a glossy, thick dark chocolate ganache glaze.
- Chill: Pop the ganache into the refrigerator for 20 minutes to stiffen slightly until it reaches a spreadable, fudgy consistency.
3. Assemble the Core Stacking
- Base Layer: Place the bottom half of your rectangular chocolate sponge onto a clean white pastry board or long serving platter. Brush the surface lightly with a few splashes of cherry syrup or Kirsch to lock in moisture.
- The Stuffing: Spread half of your thick chocolate ganache smoothly across the sponge. Neatly press a heavy layer of the drained red cherries directly into the ganache bed.
- Middle Layer: Spread the remaining ganache over the cherries to lock them in, then carefully place the second rectangular chocolate sponge sheet right on top, pressing down gently to secure the structural levels.
4. Pipe the Chocolate Whipped Cream Crown
- Whip: In a chilled mixing bowl, combine 1.5 cups of ice-cold heavy cream, powdered sugar, and 2 tablespoons of cocoa powder. Whip on high speed for 3-4 minutes until stiff, stable, and velvety folds form. Transfer into a pastry bag fitted with a wide closed-star or wavy ribbon tip.
- Pipe: Pipe continuous, elegant zigzag rosettes down the entire length of the cake in two parallel rows along the outer borders, leaving a clean channel down the center.
5. Garnish and Slice Cleanly
- Shavings: Use a vegetable peeler against a block of dark chocolate to create paper-thin, crisp dark chocolate curls. Pile them heavily down the center channel between the cream rosettes.
- Top Alignment: Place a neat, symmetrical row of your remaining glossy red glacé cherries directly along the center of the chocolate shavings.
- Serve: Pop the cake in the fridge for 30 minutes to let the layers weld together firmly. When ready to serve, dip a sharp chef’s knife into hot water, wipe it dry, and cut clean, beautiful rectangular slab slices!
Chef’s Tips for Success
- Clean-Cut Slices: To achieve that perfectly flush, geometric bakery-style cross-section shown in the photos, always wipe your knife blade completely clean with a warm, wet cloth after every single cut. If you don’t clean the blade, the dark ganache will smear across the light brown cream folds.
- Thoroughly Dry the Cherries: Make sure to dump your canned cherries into a strainer and pat them completely dry with paper towels before pressing them into the internal ganache. If the cherries are too wet with syrup, they will create slippery pockets that cause the top cake layer to slide off when handled.
- The Coffee Secret: Adding hot coffee or boiling water at the very end of the cake batter activates and blooms the cocoa powder particles. It opens up the deep aromatic flavor of the chocolate, ensuring the sponge cake doesn’t taste flat or overly sugary.