Use this recipe to make Flourless Chocolate Espresso Cake.
Combine chocolate, butter, and vanilla in a bowl. Bring cream, sugar, espresso powder, and salt to a boil in a small saucepan, stirring until sugar and espresso powder are dissolved. Pour over chocolate mixture and whisk until smooth.
Glaze can be made up to 3 days ahead and stored in refrigerator. Rewarm, stirring until smooth, in a bowl set over a saucepan of simmering water.