1. Preheat your oven to 350°F (175°C). Grease and flour a 9-inch square baking pan.

2. In a medium bowl, whisk together the flour and granulated sugar. Add the softened butter and use a fork or your fingers to work it into the dry ingredients until the mixture resembles coarse crumbs.

3. In a separate bowl, beat the eggs until light and fluffy. Gradually add the eggs to the flour mixture, mixing until just combined. Stir in the strong coffee.

4. Pour the batter into the prepared baking pan and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake to cool completely.

5. In a medium saucepan, heat the heavy cream over medium heat until it just starts to simmer. Remove from heat and add the chopped chocolate. Stir until the chocolate is melted and the mixture is smooth. Allow the ganache to cool and thicken slightly.

6. In a large bowl, beat the softened butter until light and fluffy. Gradually add the powdered sugar and beat until well combined and creamy.

7. Cut the cooled cake horizontally into three even layers. Place one layer on a serving plate and spread half of the chocolate ganache over the top. Top with another cake layer and spread the remaining ganache over it. Place the final cake layer on top.

8. Frost the top and sides of the cake with the buttercream. Refrigerate the cake for at least 2 hours before serving to allow the layers to set.