The original financier was an almond pastry created by a 19th-century Parisian pastry chef for his wealthy banker clients. This chocolate version is worth its weight in gold.
- 3/4 cup (1 1/2 sticks) unsalted butter
- 1/2 cup all purpose flour
- 1/4 cup unsweetened cocoa powder
- 6 large egg whites, room temperature
- 1 tablespoon light corn syrup
- 1 teaspoon vanilla extract
- 1 cup finely ground blanched almonds (about 4 ounces)
- 4 ounces bittersweet (not unsweetened) or semisweet chocolate, finely chopped
- 6 ounces bittersweet (not unsweetened) or semisweet chocolate, finely chopped
- 3/4 cup heavy whipping cream
- 2 tablespoons (1/4 stick) unsalted butter, cut into 1/2-inch cubes
Preheat oven to 350°F. Butter two 8-inch round cake pans with 1 1/2-inch-high sides. Line bottoms with parchment or waxed paper round. Melt 3/4 cup butter in medium saucepan over medium heat. Cook until light brown, swirling pan occasionally, about 5 minutes. Cool.
Meanwhile, sift flour, cocoa, and salt into medium bowl. Whisk egg whites in large bowl to blend. Add sugar; whisk to blend. Whisk in corn syrup and vanilla. Add flour mixture; whisk just to blend. Add ground almonds; whisk just to blend. Using whisk, fold in browned butter, then chopped chocolate. Divide batter between prepared pans, smoothing tops.
Bake cakes until firm to touch and tester inserted into center comes out clean, about 23 minutes. Cool cakes on rack 5 minutes. Invert cakes onto rack; peel off paper. Cool completely.
Place chocolate in small metal bowl. Bring cream to boil in small saucepan. Pour cream over chocolate; whisk until smooth. Add butter, 1 piece at a time, gently whisking to blend between additions, adding as little air as possible. Transfer 2/3 cup ganache to heatproof 1-cup measure with spout. Place bowl with remaining ganache over bowl of ice water. Stir until semi-firm and thick enough to spread. Set aside for filling.
Line rimmed baking sheet with foil. Place rack on sheet. Place 1 cake, flat side down, on rack. Strain apricot jam into small skillet; bring to boil. Spoon warm jam over cake, spreading evenly almost to edge. Let cool 5 minutes. Drop filling by teaspoonfuls all over cake, then spread in even layer. Place second cake atop filling, bottom side up. If glaze is too firm to pour, rewarm in microwave at low power in 15-second increments until pourable. Pour over cake, allowing glaze to drip down sides and using offset spatula to spread glaze evenly over sides of cake. Chill cake 2 hours. DO AHEAD Can be made 2 days ahead. Cover with cake dome; keep chilled.
Arrange sliced almonds atop cake.