Line 9 x 13 pan with graham crackers. Cover with 1/2 of the pudding mixture. Repeat with another layer of graham crackers. Repeat with pudding mixture. Top with final layer of graham crackers.
Melt together: 2 squares Baker's unsweetened chocolate and 3/4 stick butter.
Add and mix: 2 tablespoons white corn syrup, 1 1/2 cup sifted confectioner's sugar, 1 teaspoon vanilla and 3 tablespoons half and half. Pour over top graham cracker layer. Cover and refrigerate 24 hours.