Step 1
Preheat the oven to 300 degrees F (150 degrees C).
Step 2
Combine chopped chocolate and hot coffee in a bowl. Stir occasionally until chocolate is melted and mixture is smooth. Set aside.
Step 3
Sift sugar flour cocoa powder baking soda baking powder and salt together in a large bowl.
Step 4
Beat eggs in a bowl using an electric mixer until slightly thickened and lemon-colored. Slowly add oil buttermilk vanilla extract and melted chocolate mixture. Beat until well combined. Add sugar-flour mixture; beat on medium speed until just combined. Divide batter between the prepared cake pans.
Step 5
Bake in the preheated oven until a toothpick inserted into the center comes out clean 1 hour to 1 hour and 10 minutes. Let cool completely in pans on wire racks about 30 minutes. Invert layers onto racks.
Step 6
While cakes are cooling bring heavy cream sugar and corn syrup to a boil over low heat in a small saucepan. Whisk until sugar dissolves. Add chocolate; whisk until melted. Add butter; whisk until smooth. Let ganache frosting cool until spreadable about 10 minutes.
Step 7
While frosting and cakes continue to cool puree raspberries in a food processor. Press through a fine mesh strainer with the back of a spoon into a saucepan. Pour in sugar and cornstarch; bring to a boil over medium-low heat. Cook until thickened and reduced 5 to 7 minutes. Stir in lemon zest. Remove raspberry filling from heat.
Step 8
Cut each cake layer in 1/2 horizontally to produce 4 equal layers. Spread 1/3 raspberry filling onto each of 3 layers and stack. Place top layer onto cake. Spread ganache frosting evenly from center of top layer down the sides of the cake.