1 prebaked 9-inch pie shell
4 ounces German chocolate
1 cup (2 sticks) butter, softened
1 1/2 cups sugar
1 teaspoon good vanilla
4 eggs, at room temperature
3 cups whipped cream
1 chocolate bar (good quality), roughly chopped or shaved
Heat chocolate in a microwave-safe bowl in 20-second intervals, stirring between, until completely melted. Set aside, and let cool for about 10 minutes until it is room temperature.
In a large mixing bowl, cream together the butter and the sugar on medium-high speed until fluffy, about 1 to 2 minutes. Add the cooled melted chocolate to the butter/sugar mixture. Beat the mixture on medium-low speed until completely combined. Add the vanilla, and mix until combined.
Switch to the whisk attachment of the mixer. Add one egg, and beat for 5 minutes on medium speed. Repeat with the remaining eggs, beating the mixture for 5 minutes after the addition of each egg. Pour the filling into a baked pie shell, using a spatula to evenly spread out the filling. Refrigerate for at least 2 hours, or until chilled before serving.
Top with whipped cream, and garnish with chocolate shavings.