- 6 slices firm whole-wheat sandwich bread
- 3 tablespoons all-purpose flour
- 1/4 teaspoon salt
- 4 large eggs at room temperature
- 2/3 cup packed light brown sugar
- 1 teaspoon vanilla
- 1/2 stick (1/4 cup) unsalted butter, melted and cooled slightly
- 2/3 cup heavy cream
- 7 oz fine-quality bittersweet chocolate (not unsweetened), finely chopped
- 3/4 cup seedless raspberry jam
- Garnish: raspberries and lightly sweetened whipped cream
- Preheat oven to 350°F. Line bottom of a buttered 15- by 10- by 1/2- to 1-inch baking pan with wax or parchment paper. Butter paper, then dust with flour, knocking out excess.
- Arrange bread slices in 1 layer on a baking sheet and bake in middle of oven, turning over once, until dry and pale golden, about 15 minutes. Cool, then break into pieces. Pulse bread in a food processor until finely ground, then add flour and salt and process until very finely ground.
- Beat together eggs, brown sugar, and vanilla with an electric mixer at high speed until pale, very thick, and tripled in volume (about 5 minutes with a standing mixer or 10 minutes with a handheld). Gently fold in crumbs in 4 batches. Spoon 1 cup batter into a small bowl. Stir in butter, then fold back into remaining batter.
- Spread batter evenly in baking pan and rap pan twice on work surface to eliminate air bubbles. Bake in middle of oven until top is dry to the touch and pale golden around edges, 10 to 13 minutes. Transfer pan to a rack and loosen sides of cake with a knife, then cool 15 minutes. Place rack over cake and invert cake onto rack. Discard wax paper and cool.
- Heat cream and chocolate in a small heavy saucepan over low heat, stirring, until chocolate is melted and smooth, about 5 minutes (do not boil). Chill ganache, stirring occasionally, until thick enough to spread, about 1 hour.
- Invert cake onto a cutting board and cut crosswise into 5 equal strips. Put 1 strip on a platter and spread top with one fourth of jam. Repeat with 3 more layers of cake and jam. Top with remaining cake layer, smooth side up.
- Frost top and sides of cake with ganache and chill cake until ganache is firm, at least 15 minutes.