Preheat the oven to 400 degrees F. Add instant coffee to melted butter. Set aside.
Beat the egg whites until stiff, set aside. Beat the egg yolks until lemon colored in an upright mixer. Add the sugar to the egg yolks and beat until combined. Add the brandy, vanilla, melted butter, and chocolate. Add the flour, just to combine. Fold in the egg whites and walnuts.
Pour into a greased and floured 9-inch springform pan and bake about 20 minutes. Center will be soft. Serve with whipped cream.