Birthday Cake Recipe

Prepare

Preheat the oven to 350°F (175°C). Grease and flour a 9-inch heart-shaped cake pan (or two 8-inch round pans if heart pan unavailable). Line the bottom with parchment for easy release.

Dry Ingredients

In a large bowl whisk together 2.5 cups all-purpose flour, 1.75 cups granulated sugar, 2 tablespoons unsweetened cocoa powder, 1.5 teaspoons baking soda, and 1 teaspoon salt until evenly distributed.

Wet Ingredients

In a separate bowl whisk 1 cup buttermilk, 0.75 cup vegetable oil, 2 large eggs, 2 teaspoons vanilla extract, 1 teaspoon distilled white vinegar, and 2 tablespoons red food coloring until smooth and uniform in color.

Combine Batter

Make a well in the dry ingredients and pour in the wet mixture. Stir gently with a spatula until just combined and no large streaks of flour remain. Do not overmix. Batter will be fairly loose.

Bake

Pour batter into the prepared heart pan (or divide between pans). Smooth the top. Bake on the center rack for 28–35 minutes (if using two 8-inch rounds check at 25 minutes) or until a toothpick inserted into the center comes out with a few moist crumbs. Rotate pan halfway through baking for even browning.

Cool

Allow cake to cool in the pan on a wire rack for 10 minutes. Run a knife around the edges, invert onto the rack, remove parchment, and cool completely (about 1 hour) before filling and frosting.

Cook Raspberry Filling

Combine 10 ounces raspberries, 0.5 cup granulated sugar, and 1 tablespoon lemon juice in a small saucepan over medium heat. Bring to a simmer, stirring occasionally, and cook until the berries break down, about 6–8 minutes.

Thicken

Mix 1 teaspoon cornstarch with 1 tablespoon cold water to make a slurry. Stir the slurry into the simmering raspberries and continue to cook 1–2 minutes until the mixture thickens. Remove from heat and let cool to room temperature; the filling will set more as it cools.

Strain (optional)

For a smoother filling, press the cooled raspberry mixture through a fine-mesh sieve to remove seeds. Reserve about 1/2 cup of whole raspberries for garnish if desired.

Melt White Chocolate

Place 8 ounces chopped white chocolate in a heatproof bowl. Melt gently over a double boiler or in 20–30 second bursts in the microwave, stirring until smooth. Let the melted chocolate cool to lukewarm (so it will not melt the butter).

Cream Butter

In a large bowl using a hand or stand mixer fitted with the paddle or whisk, beat 1 cup softened unsalted butter on medium speed until pale and fluffy, about 2–3 minutes.

Add Chocolate and Sugar

With the mixer on low, slowly add the cooled melted white chocolate and 4 cups powdered sugar in three additions, scraping down the bowl between additions.

Adjust Texture

Add 3 tablespoons heavy cream, 1 teaspoon vanilla extract, and 1/4 teaspoon salt. Beat on medium-high until smooth and spreadable, 2–3 minutes. If frosting is too thick, add additional teaspoon(s) of cream; if too thin, add a little more powdered sugar until you reach a pipeable consistency.

Level and Slice

If the cake domed during baking, level the top with a serrated knife. If using one heart layer, slice horizontally into two even layers. If using two rounds, trim to create even layers. Place the bottom layer on a cake board or serving plate.

Brush with Syrup (optional)

Lightly brush the cake layers with 1/4 cup simple syrup if you want extra moisture.

Fill with Raspberry

Spread about 1/3 of the white chocolate buttercream on the bottom layer, then spoon 3–4 tablespoons of the cooled raspberry filling in the center, leaving a 1/2-inch border so the filling won't ooze out. Smooth the buttercream over the filling to seal. Add the top layer and press gently.

Crumb Coat

Apply a thin crumb coat of buttercream over the entire cake to trap crumbs. Chill the cake in the refrigerator 20–30 minutes to set the crumb coat.

Final Frosting

Apply a generous final layer of white chocolate buttercream, smoothing with an offset spatula. Use a piping bag to create decorative borders if desired.

Decorate

Press 1/2 cup white chocolate shavings around the base or the top edge of the cake. Arrange whole raspberries on top (about 12) and drizzle a spoonful of the remaining raspberry filling in the center or use it to make small dollops. Refrigerate 30 minutes to set the buttercream before serving.

Serve

Bring cake to room temperature for 30 minutes before slicing. Serves 8–10.