To make the crust, grind the graham crackers in a food processor or just crush them with a rolling pin. You should get about 1 ⅔ cups crumbs. Pour into a mixing bowl and stir in the sugar. Add the softened butter and mix until mixture comes together when pinched. Press into a 9 inch deep dish glass pie dish. Keep chilled until ready to use.

To make the filling, combine the cocoa powder and cornstarch in a large (3 quart) saucepan that is not yet set over heat. Add the water and whisk until smooth. Whisk in the Eagle Brand and egg yolks until smooth. Put the saucepan on the stove and turn heat to medium. Cook, whisking constantly, until mixture thickens (it should take about 5 minutes). When thick and bubbling, continue whisking for another 30 or 40 seconds, then remove from the heat and whisk in the butter. When butter is melted, whisk in vanilla.

Set a piece of wax paper over the surface and let cool for about 5 to 8 minutes (you don't want the super hot filling to melt the butter in the crust) before pouring into the pie shell crust. Chill the pie for several hours. Pipe sweetened whipped cream around the edges or if you prefer, spread it all over the top.