Preheat oven to 350°F. Butter and flour a 9” round cake pan.

In a saucepan over lowest heat, melt the chocolate and butter. Remove from heat and stir in the powdered sugar, then the flour and instant coffee powder. Stir in the egg yolks one at a time.

In another bowl, beat the egg whites with a pinch of salt until stiff peaks form. Fold in the egg whites into the chocolate mixture just until mixed.

Immediately pour this batter into the prepared pan and bake for 30 minutes, or until toothpick comes out clean.

Let the cake cool and serve with powdered sugar or whipped cream.