This high school graduation cake is a classic, crowd-pleasing yellow sheet cake with chocolate fudge frosting, decorated to look like a diploma. It’s baked in a single 9×13-inch pan, so it’s simple to transport and serve to a crowd. The cake is moist, the frosting is rich and shiny, and the whole thing comes together with basic ingredients and no fancy equipment.
Ingredients
- 2 1/2 cups (300 g) all-purpose flour
- 2 1/2 tsp baking powder
- 1/2 tsp salt
- 1 cup (2 sticks, 226 g) unsalted butter, softened
- 1 3/4 cups (350 g) granulated sugar
- 3 large eggs, at room temperature
- 1 tbsp vanilla extract
- 1 1/4 cups (300 ml) whole milk, at room temperature
- 1/2 cup (60 g) unsweetened cocoa powder
- 1/2 cup (120 ml) heavy cream
- 2 cups (240 g) powdered sugar, sifted
- 1/4 cup (60 g) unsalted butter, softened (for frosting)
- 1/4 cup (60 ml) hot water (for frosting)
- 1/2 cup (50 g) chocolate sprinkles or mini chocolate chips (for decoration)
Instructions
- Preheat the oven to 350°F (175°C). Grease a 9×13-inch baking pan with butter or nonstick spray, then line the bottom with parchment paper.
- In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
- In a large bowl, beat the softened butter and sugar with an electric mixer on medium speed until light and fluffy, about 2-3 minutes. Add the eggs one at a time, beating well after each addition, then beat in the vanilla extract.
- With the mixer on low speed, add the flour mixture in three additions, alternating with the milk, starting and ending with the flour. Mix just until combined—do not overmix.
- Pour the batter into the prepared pan and smooth the top. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan on a wire rack for 15 minutes, then turn it out onto the rack to cool completely (about 1 hour).
- While the cake cools, make the frosting. In a medium saucepan, whisk together the cocoa powder and heavy cream. Cook over medium heat, stirring constantly, until the mixture is smooth and slightly thickened, about 2 minutes. Remove from heat and stir in the powdered sugar and softened butter until smooth. Add the hot water, a tablespoon at a time, until the frosting is spreadable but still thick. Let it cool for 10 minutes.
- Once the cake is completely cool, place it on a serving platter. Spread the frosting evenly over the top and sides. Use a spatula to create a smooth surface.
- To decorate like a diploma: use a knife or offset spatula to make a diagonal line across the cake from one corner to the opposite corner, dividing the top into two triangles. Cover one triangle with chocolate sprinkles (or mini chips) to represent the dark part of the diploma, and leave the other triangle plain. Tie a ribbon around the middle if you like.
Tips
- Room temperature ingredients: Bring the eggs, milk, and butter to room temperature before starting. This helps the batter emulsify and creates a more tender crumb.
- Don’t overmix: Once you add the flour, mix only until no streaks remain. Overmixing develops gluten and makes the cake tough.
- Frosting consistency: If the frosting is too thick, add more hot water a teaspoon at a time. If it’s too thin, chill it for 10 minutes before spreading.
- Substitutions: For a dairy-free version, use plant-based butter and milk (like oat or almond) and a dairy-free heavy cream substitute. The texture will be slightly denser but still good.
Serving Suggestions
Serve this cake at room temperature, cut into squares. It pairs wonderfully with vanilla ice cream or fresh berries. For a graduation party, set it on a table with other desserts and let guests serve themselves. You can also add a small flag or a “Class of� topper for a festive touch.
Variations
- White cake version: Omit the cocoa powder and use 1/2 cup (120 ml) milk instead of heavy cream for a classic white frosting. Add 1 tsp almond extract for a different flavor.
- Berry layer: After the cake cools, slice it horizontally into two layers and spread a layer of strawberry jam or fresh sliced strawberries with whipped cream between the layers.
- Cupcakes: Bake the batter in lined muffin tins for about 18-20 minutes, then frost and decorate each one as a mini diploma.
- Chocolate cake: Replace 1/2 cup (60 g) of the all-purpose flour with an equal amount of cocoa powder to make a chocolate base.
Storage and Reheating
Store the frosted cake in an airtight container at room temperature for up to 2 days, or in the refrigerator for up to 4 days. If refrigerated, let it sit at room temperature for 30 minutes before serving to soften the frosting. The cake can also be frozen (unfrosted or frosted) for up to 2 months. Wrap it tightly in plastic wrap and then foil. Thaw overnight in the refrigerator before serving.
Frequently Asked Questions
Can I make this cake ahead of time? Yes, you can bake the cake a day ahead, wrap it tightly in plastic wrap, and store it at room temperature. Frost it the day of the party for the freshest look.
Can I use a different frosting? Absolutely. Cream cheese frosting, vanilla buttercream, or a simple glaze all work well. If using a glaze, pour it over the cake while still slightly warm for a smooth finish.
How do I get clean slices? Use a long, thin knife and wipe it clean between cuts. For the neatest edges, chill the cake for 20 minutes before slicing.
Can I make this as a layer cake? Yes, double the recipe and bake in two 9-inch round pans for about 25-30 minutes. Stack with frosting between layers and on top.
What if I don’t have a 9×13 pan? You can use two 8-inch square pans; adjust baking time to about 25 minutes. Check for doneness with a toothpick.
Is it safe to leave the cake out during the party? Yes, this cake is safe at room temperature for up to 2 hours. After that, refrigerate any leftovers.
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