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1
Preheat oven to 350F.
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2
Line bottom of a buttered 15- by 10- by 1/2- to 1-inch baking pan with wax or parchment paper.
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3
Butter paper, then dust with flour, knocking out excess.
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4
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.
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5
Cool, then break into pieces.
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6
Pulse bread in a food processor until finely ground, then add flour and salt and process until very finely ground.
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7
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).
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8
Gently fold in crumbs in 4 batches.
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9
Spoon 1 cup batter into a small bowl.
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10
Stir in butter, then fold back into remaining batter.
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11
Spread batter evenly in baking pan and rap pan twice on work surface to eliminate air bubbles.
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12
Bake in middle of oven until top is dry to the touch and pale golden around edges, 10 to 13 minutes.
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13
Transfer pan to a rack and loosen sides of cake with a knife, then cool 15 minutes.
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14
Place rack over cake and invert cake onto rack.
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15
Discard wax paper and cool.
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16
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).
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17
Chill ganache, stirring occasionally, until thick enough to spread, about 1 hour.
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18
Invert cake onto a cutting board and cut crosswise into 5 equal strips.
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19
Put 1 strip on a platter and spread top with one fourth of jam.
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20
Repeat with 3 more layers of cake and jam.
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21
Top with remaining cake layer, smooth side up.
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22
Frost top and sides of cake with ganache and chill cake until ganache is firm, at least 15 minutes.
