1. Prepare 20 cm pastry shell.
2. Cream butter in medium-size bowl and gradually add sugar, creaming well after each addition.
3. Cool melted chocolate; blend into butter-sugar mixture with instant coffee and vanilla.
4. Add eggs, one at a time, beating VERY WELL after each addition. (Use an electric beater or mixer, for you'll need to beat in each egg 5 minutes to make mixture creamy, thick, and fluffy.)
5. Turn into baked pastry shell; chill 1 2 hours. Just before serving, whip cream and garnish pie.