CHOCOLATE ORANGE POPPY-SEED LAYER CAKE

Steps:

• Make the filling: In a bowl, stir together the sour cream, heavy cream and the granulated sugar (first 3 ingredients), and let the mixture stand, covered with plastic wrap, at room temperature for 24 hours. In a metal bowel set over barely simmering water melt the chocolate, stirring until it is smooth and let it cool. Whisk the 8 ounces chocolate, the 2 tsp zest and the Grand Mariner into the cream mixture and chill the filling, covered, for 1 hour.
• Make the cake: Line a buttered jelly roll pan, 15 1/2 by 10 1/2 inches x 1 inch with wax paper, butter the paper, and dust the pan with flour, shaking out the excess. In a small bowel, stir together the buttermilk, the poppy seeds, and the zest and into another bowl sift together the flour, the baking soda, and the salt. In another bowl with an electric mixer cream together the butter and the sugars until the mixture is light and fluffy and beat in the egg yolks and the vanilla, beating until just combined. Add the flour mixture alternately with the buttermilk mixture to the butter mixture, beginning and ending with the flour mixture and beating well after each addition until the batter is just combined. In another bowl with cleaned beaters beat the egg whites until they just hold stiff peaks, stir one fourth of them into the batter to lighten it, and fold in the remaining whites gently but thoroughly. Pour the batter into the prepared pan, spreading it evenly, and bake the cake in the middle of a preheated 350F oven for 20-25 minutes or until the top is golden and the cake springs back when touched lightly. Let the cake cool in the pan on a rack, invert it onto the rack and remove the wax paper carefully. With a serrated knife cut the cake crosswise into 3 equal pieces.
• Make the glaze: In a heavy saucepan melt the chocolate with the butter and the cream over low heat, stirring until the mixture is smooth, and let the glaze cools to room temperature
• Assemble the cake: On a rack set over a jelly-roll pan arrange one of the cake layers, spread it with one third of the filling, and top the filling with another cake layer. Spread the cake with half the remaining filling and top it with the remaining cake layer. Spread the remaining filling onto the top and sides of the cake and chill for 30 minutes, or until filling is set. Pour the glaze evenly over the cake, smoothing it over the sides, and chill the cake for 30 min or until the glaze is set.