1. Preheat Roaster Oven to 300°F.
2. In double boiler or heavy saucepan over low heat, melt chocolate, butter, and instant coffee. Set aside.
3. In mixing bowl, beat egg whites and salt until whites hold a point but not stiff. Set aside.
4. In a mixing bowl, whisk egg yolks. Add some of the melted chocolate to the yolks, then whisking quickly, add remaining chocolate to the yolks. Stir in sugar and vanilla.
5. Add a few large spoonfuls of egg whites to the chocolate. Fold in. Add remaining whites and fold until combined.
6. Generously butter a bundt or 10-inch tube pan then generously coat with sugar. Pour in chocolate mixture. Place in roaster oven on insert rack and bake for 2 hours. The cake will rise then fall during baking.
7. Remove from oven and let sit in pan 5 minutes. Invert onto serving plate. Best if served warm with whipped cream or ice cream.