1) Preheat the oven to 350°F. Lightly grease a 9" x 9" or 11" x 7" pan.
2) To make the crust: Place all of the crust ingredients in a mixing bowl, and beat at medium speed just until thoroughly combined.
3) Press the mixture into the prepared pan, and bake for 10 minutes. Remove the pan from the oven, and set it aside to cool.
4) To make the filling: In a medium-sized mixing bowl, combine the softened butter, 1 cup of the sugar, and the vanilla, beating until smooth.
5) In a small bowl, combine the pastry cream filling mix or instant vanilla pudding mix with the milk, stirring until thick and smooth.
6) Add the pudding mix to the butter/sugar mixture, stirring to combine.
7) Add the remaining sugar, and beat until the filling is smooth. Spread it over the cooled crust, cover, and refrigerate until chilled.
8) To make the icing: Combine the chocolate and cream (or butter) in a saucepan or microwave-safe bowl. Heat until the cream is steaming. Stir until smooth.
9) Spread the frosting onto the bars. Refrigerate until the chocolate is set.
10) Cut into small bars or rectangles to serve. The bars will be very stiff when cold, but will soften quickly at room temperature.
Yield: about 25 small, rich bars.