Preheat the oven to 300℉., and grease two 10-inch cake pans, or three 8-inch cake pans. Spray the pans with nonstick spray and then line the bottoms with rounds of parchment paper- then spray the paper too.
In a medium bowl combine the chocolate with the hot coffee. Let the mixture stand, stirring occasionally, until the chocolate is melted and the mixture is smooth.
In a large bowl sift together the sugar, flour, cocoa powder, baking soda, baking powder, and salt. In another large bowl with an electric mixer beat the eggs until thickened slightly and lemon colored (about 3 minutes with a standing mixer or 5 minutes with a hand-held mixer). Slowly add the buttermilk, oil, vanilla, and melted chocolate mixture to the eggs, beating until combined well. Add the dry mixture and beat on medium speed until just combined.
Divide the batter between the pans and bake in the middle of the oven 50 to 65 minutes, or until a tester inserted in the center of the cake comes out clean.
Cool layers completely in pans on racks. Run a thin knife around the edges of the pans and invert the layers onto racks. Carefully remove the parchment paper and cool the layers completely. Cake layers may be made 1 day ahead and kept, wrapped well in plastic wrap, at room temperature.
PREPARE THE GANACHE FROSTING:
In a 1½- to 2-quart saucepan bring the cream, sugar, and corn syrup to a boil over moderately low heat, whisking until the sugar is dissolved. Remove the pan from heat and add the chocolate, whisking until the chocolate is melted. Add the butter pieces and whisk until smooth.
Transfer the frosting to a bowl and cool, stirring occasionally, until it is spreadable (It may be necessary to chill the frosting to reach a desirable spreadable consistency).
PREPARE THE FILLING:
Puree the raspberries in a food processor or blender. Press the puree through a fine-mesh strainer with the back of a spoon, removing the seeds. Heat the puree in a small pot with the sugar and cornstarch until the mixture boils, stirring constantly. As it boils, it should quickly thicken. Let cool.
ASSEMBLE THE CAKE:
Spread a thin layer of ganache frosting on 1st cake layer- followed by a layer of the raspberry filling. Top with the 2nd cake layer and repeat (if using a 3rd layer). If only using two cake layers, cover the top and sides with the remaining chocolate ganache frosting. This cake keeps, covered and chilled, up to 3 days. Bring the cake to room temperature before serving.
Notes
*If you use frozen raspberries that are already sweetened with sugar, just leave the sugar out when making the filling.
*If you only have two 9-inch round pans or two 8-inch rounds, you can choose to just make a 2-layer cake and then use the rest of the batter to make some cupcakes. Fill the pans no more than ⅔ full with batter- you don't want them to overflow when they rise while baking!