Total time: 2 hours
for the vanilla sponge:
12 tablespoons unsalted butter, softened, plus more for greasing
2 1/4 cups all-purpose flour, sifted
1 1/2 cups caster sugar
1 1/2 tablespoons baking powder
pinch of kosher salt
3 large eggs
3/4 cup whole milk
1 1/2 teaspoons vanilla extract
for the crumble:
1 1/4 cups oats
1/2 cup dark brown sugar
8 tablespoons unsalted butter, cubed and refrigerated
pinch of sea salt
for the mixed berry coulis:
1 pound 6 ounces fresh or frozen berries
2/3 cup caster sugar
for the custard:
1/4 cup caster sugar
1/4 cup cornflour
6 egg yolks
2 3/4 cups heavy cream
1 teaspoon vanilla extract
for serving and assembly:
1 cup medium sweet sherry
3/4 pound mixed berries, sliced if large
1. Make the vanilla sponge: Grease and line two cake pans and set aside. Heat the oven to 350°F|180°C. In a large bowl, whisk the flour, sugar, baking powder, and salt together. Add in the butter and beat until it looks like a fine crumble, 2 to 3 minutes.
2. Add the eggs and beat until just incorporated. Add the milk and vanilla and beat until smooth and combined, 2 to 3 minutes. Divide the batter evenly between the prepared cake pans and bake until lightly golden, about 20 minutes. Let the cakes cool in their pans for 10 minutes before turning out onto a wire rack to cool completely.
3. Make the crumble: Place the oats, brown sugar, butter, and salt in a medium bowl. Using your fingers, break everything up together to form small pea-sized crumbles. Spread into an even layer on a parchment paper-lined baking sheet and freeze for 10 minutes, then bake until golden, about 10 minutes. Allow to cool completely before breaking up into smaller pieces.
4. Make the mixed berry couli: In a small saucepan, combine the berries, sugar, and 2/3 cup|150 ml water and bring to a boil. Reduce the heat to maintain a simmer and cook, stirring occasionally, until thick, about 25 minutes. Cool slightly, then transfer to a blender and purée until smooth. Strain through a fine mesh sieve and set couli aside.
5. Make the custard: In a small bowl, whisk together the cornflour, sugar, and egg yolks until combined. Meanwhile, heat the cream in a small saucepan over medium-high until bubbles start to form around the edge. While whisking constantly, pour about 1/2 cup|125 ml of cream into the egg mixture, then pour the egg and cream mixture back into the saucepan with the rest of the cream. Reduce the heat to medium and continue to cook the custard, whisking constantly, until thick, about 3 minutes. Pass the custard through a fine mesh sieve and into a bowl, cover with plastic wrap directly on its surface, and set aside to cool.
6. Assemble the trifle: In a medium bowl, whisk together the couli with the sherry. Break the cake into pieces and place half of one layer of cake into the bottom of a large bowl or trifle dish. Ladle some custard on top, sprinkle with fresh berries, and drizzle with the couli and sherry mixture. Repeat layering until you get to the top, finishing with berries. Sprinkle wit crumble and enjoy!