Ingredients
350 g unsalted butter, room temperature, plus more for pans
100 g walnuts
250 g (or more) all-purpose flour
250 g caster or granulated sugar
100 g light brown sugar
7 medium eggs
5 tsp. baking powder
1 tsp. pure vanilla extract
30 mL whole milk
200 g fresh or frozen blackberries
2 tbsp. black currant jam
2 tbsp. light brown sugar
250 g mascarpone
200 mL heavy cream
30 g caster or granulated sugar
1 tsp. pure vanilla extract
150 g black currant jam, divided
200 g mixed fresh or frozen berries, such as blackberries, cherries, and/or red currants
3 sprigs rosemary or thyme
Confectioners’ sugar, for dusting
Preparation
Step 1Preheat oven to 180°C (350°F). Line 3 (21-centimeter/8") round pans with parchment, then grease with butter.Step 2Spread walnuts on a baking sheet and bake until toasted and fragrant, 12 to 15 minutes. Let cool.Step 3Transfer walnuts to a food processor. Add flour and pulse until finely ground.Step 4Using an electric mixer on medium-high speed, in a medium bowl, beat butter, caster sugar, and brown sugar until light and fluffy. In a large liquid measuring cup or medium bowl, lightly beat eggs. Gradually add to bowl, beating to combine. If mixture starts to curdle, add a few tablespoons more flour. Add baking powder and vanilla and mix with a large spoon to combine. Add milk and mix until smooth.Step 5 Divide batter among prepared cake pans. Smooth top with an offset spatula, then create a small indent in the center so cake has a flat top and isn’t peaked while it bakes.Step 6Bake cakes until golden and spring back to a light touch, 18 to 20 minutes. Transfer pans to a wire rack and let cool completely.
Step 1In a small pot over low heat, cook blackberries, jam, and brown sugar, stirring occasionally, until blackberries are softened but remain whole and aren’t broken down. Let cool.Step 2Using electric mixer on medium-high speed, in a medium bowl, beat mascarpone, cream, caster sugar, and vanilla until combined and holds its shape.
Step 1Trim cake layers to form a flat top, if needed. Arrange first layer on a platter. Spread with half of jam, top with half of cream, then half of blackberries, spreading right to the edges.Step 2Place second layer on top and repeat with remaining jam, cream, and berries.Step 3Top with third layer. Arrange mixed berries in a heap in the center of cake. Decorate with rosemary sprigs. Generously dust with confectioners’ sugar.Step 4Make Ahead: Cake can be made 2 days ahead. Store in an airtight container and refrigerate.
