- With the rack in the middle position, preheat the oven to 350°F (180°C). Butter and line two 8-inch (20 cm) springform pans with parchment paper.
- In a bowl, combine the flour, baking soda, baking powder and salt. Set aside.
- In another bowl, combine the eggs, sugar, buttermilk, oil and vanilla with a whisk. Set aside.
- In a small bowl, combine the cocoa powder and coffee with a whisk. Add to the egg mixture. Add the dry ingredients and stir until smooth. Spoon the batter into the prepared pans. Bake for 45 to 50 minutes or until a toothpick inserted into the centre of the cake comes out clean. Let cool completely before unmoulding.
- In a saucepan, bring the cream and corn syrup to a boil.
- In a bowl, pour the hot cream mixture over the chocolate. Let melt for 2 minutes. Stir until the ganache is smooth. Refrigerate for about 1 hour or until it has thickened and is still spreadable, stirring four or five times.
- On a work surface, cut and remove the rounded tops of each cake. Cut each cake in half horizontally to make four slices. With a spatula, spread the ganache evenly over the surface of each slice. Layer the four slices and place on a cake stand.
This cake keeps well for up to 3 days at room temperature under a cake dome.