Triple Raspberry and Lemon Birthday Cake

To make the cake layers, set a rack in the middle of the oven and preheat the oven to 350°F (175°C). If your oven isn’t wide enough to accommodate two pans side by side, adjust two racks just above and below the middle.

Butter the bottoms and sides of two 8” (20.5cm) round cake pans, line the bottoms with parchment rounds and wrap dampened cake strips around the pans if you have them. Sift together the flour, baking powder and salt into a medium bowl.

In a medium bowl, whisk the milk, yogurt and vanilla until smooth. Using a fine tooth rasp grater, grate the zest of the lemons (avoiding the bitter white pith) directly into the bowl of a stand mixer. Add the sugar and use your fingertips to rub the zest into the sugar. Attach the bowl and fit the paddle attachment onto the mixer.

Add the butter and beat at medium-high speed until light and fully, about 3 minutes. Add the egg whites and beat until blended, about 3 minutes, scraping down the sides of the bowl as needed. Reduce the speed to low and beat in a third of the flour mixture, followed by half of the milk mixture. Repeat with another third of the flour mixture and the remaining milk mixture. Finally, add the remaining flour mixture and beat just until incorporated.

Remove the bowl from the mixer and scrape down the sides of the bowl with a silicone spatula, reaching down to the bottom to incorporate any unmixed dry ingredients.

Divide the batter evenly between the prepared pans (about 19.8oz/560g each) and spread them evenly with a small offset spatula.

Bake until a wooden toothpick inserted into the centres comes out clean, about 30 minutes, rotating the pans top to bottom after 20 minutes if they are on different levels. Set the pans on a wire rack to cool for 30 minutes. Pressing firmly against the pans, run a small knife around the edges to loosen the cakes, invert onto wire racks and remove the parchments. Invert the layers a second time onto the racks and let cool completely.

The cakes will keep, wrapped airtight, at room temperature for up to 2 days or in the freezer for up to 2 months. Thaw overnight in the refrigerator before using.

To make the raspberry buttercream, in a medium bowl, mash the berries and 6 tablespoons (75g) of the sugar with a silicone spatula and let stand until the berries release their juices and the sugar dissolves, about 15 minutes. Scrape the berries and their juices into a fine mesh strainer set over a medium saucepan and strain, pressing hard with the spatula until only the seeds are left in the strainer. Scrape any puree clinging to the bottom of the strainer into the pan. Discard the seeds. You will have about a cup (240g) of sweetened berry puree.

Add the lemon juice to the puree, set the pan over medium-high heat and bring to a boil, stirring frequently. Reduce the heat to medium and cook until the juices thicken and the puree is reduced to a little over ½ cup (130g), about 12 minutes, frequently stirring and scraping the bottom of the pan with a silicone spatula to prevent scorching. Scrape the puree into a small heatproof bowl and let cool for 15 minutes, stirring occasionally. Cover the bowl tightly with plastic wrap, pressing it directly onto the surface of the puree to prevent a skin from forming. Keep at room temperature while you make the meringue.

The raspberry puree will keep in the refrigerator for up to a month. Let stand at room temperature for 20 minutes and whisk until smooth before using.

In the bowl of a stand mixer set over a medium saucepan filled with 2” (5cm) of barely simmering water, whisk the egg whites and the remaining 1¼ cup (250g) of sugar until the sugar dissolves and the mixture registers 162°F (72°C) on an instant read thermometer, 10-15 minutes. Attach the bowl and fit the whisk attachment onto the mixer and beat at medium-high speed until the meringue is thick, glossy and completely cool, about 10 minutes. Add the butter in five equal parts, beating until blended after each addition. After the last addition, beat until the buttercream is thick and smooth, about 5 minutes. Add the raspberry puree and beat until blended, about a minute. You will have about 5½ cup (34oz/ 965g) of buttercream.

The buttercream will keep, wrapped airtight, at room temperature for up to 24 hours, or in the refrigerator for up to 5 days. Bring to room temperature and whisk at medium-low speed until smooth before using.

To assemble and decorate the cake, with a large serrated knife, trim away the top crusts of the cakes and slice each cake in half horizontally. You will have two layers with a bottom crust and two with no crust.

Dab a bit of buttercream in the centre of a serving plate to prevent the cake from sliding and centre a bottom crust cake layer over it, cut side up. Slide wide strips of parchment paper beneath the cake on all sides to protect the plate. Put a cup (6.2oz/175g) of buttercream on the cake and spread it with a large offset spatula evenly over the cake, going just past the edge. By hand, gently halve a third of the fresh raspberries (5.3oz/150g) lengthwise (top to bottom) and evenly arrange them, cut side down, on the buttercream, leaving a 0.5” (1.3cm) border all around. Repeat these steps twice more using the no-crust layers and all of the raspberries, then top the cake with the bottom crust layer, placing it crust side up. Put a cup (6.2oz/175g) of buttercream on top and spread it in a thin, even layer over the top and sides of the cake. Don’t worry about how the cake looks at this point; this is the crumb coat, which helps to trap the crumbs so that you may apply the final coating of buttercream smoothly and cleanly. Refrigerate the cake, uncovered, until the crumb coat sets, about 15 minutes.

Put the remaining 1½ cup (9.3oz/265g) of buttercream on top of the crumb coated cake and spread it evenly over the top and sides of the cake. Put the freeze-dried raspberries into a mesh strainer set over a medium bowl and use your fingertips to gently break them into small pieces. Shake the strainer over the bowl to strain out any fine powder (enjoy it with yogurt or add it to a smoothie). Scatter the berry pieces in the strainer over the cake to cover the top. To cover the sides, grab small handfuls of berry pieces and gently press them into the buttercream, rotating the cake as you go. Carefully slide the parchment strips out from under the cake.

Serve at room temperature or slightly chilled.

The cake will keep under a cake dome at room temperature for up to 24 hours, or may be refrigerated, covered with an aluminium foil tent (poke holes in the foil with a fork to prevent condensation), for up to 2 days. Before serving, let the chilled cake stand at room temperature, uncovered, until the buttercream softens, about 45 minutes.