Bake the pastry shell (or graham cracker or chocolate cookie crust) in 450 degree oven for 10-12 minutes. Melt the chocolate in double boiler or microwave. Let cool.
In separate bowl beat together sugar and butter about 4 minutes with a mixer, until fluffy. Beat in chocolate or vanilla. Add eggs, one at a time, beating on medium speed for 2 minutes after each addition. Turn into shell. Chill several hours or overnight, until set. Garnish with whipped cream or chocolate curls.