Flourless Chocolate Cupcakes with Whipped Cream

3/4 cup butter
1 1/2 cups chocolate chips
6 eggs, separated 
1/2 cup sugar

Melt butter and chocolate in a metal bowl set in a pan of simmering water on low heat.  Stir constantly until melted, then remove from heat.  Wait a few minutes, then stir in egg yolks.  In a separate bowl, beat egg whites until they hold soft peaks.  Gradually add sugar and beat until mixture is stiff and glossy.  Whisk some of the whites mixture into the chooclate, and then pour back into the whites while strring gently.  Fill cupcake liners.  Bake at 275 for 25 minutes, or until cakes look set and an insterted toothpick comes out mostly clean.  

whipped cream
espresso powder

Top room-temperature cupcakes just before serving with a dollop of whipped cream and a sprinkle of espresso powder.