Bittersweet Chocolate Cake

Preheat the oven to 350 degrees. Butter and flour an 8-inch springform pan.

Place a large heatproof bowl over a pot of simmering water, making sure the water doesn't touch the bowl. Put the butter and chocolate in the bowl, stirring occasionally, until the chocolate melts. Take the bowl off the heat and set aside.

First, whisk the sugar into the chocolate mixture, then whisk in the eggs, coffee and ¹⁄₂ tsp salt, whisking until the mixture is combined and smooth. Sprinkle in the flour and fold it in with a rubber spatula until it's incorporated.

Pour the batter into the prepared pan and place it on a sheet pan. Bake for 30 to 40 minutes, until the top puffs up and cracks and the cake doesn't wobble when you jiggle the pan. A toothpick will not come out clean. Remove from the oven and cool completely on a baking rack. The cake will deflate as it cools. Run a small knife around the cake and remove the sides of the pan. Cut the cake in wedges and serve warm or at room temperature with vanilla ice cream.