Beat egg yolks in a small bowl, then briskly stir a small amount of the hot mixture (about 1/2 cup) into this mixture. Add egg yolk mixture back into the hot mixture in top of double boiler and stir in butter and vanilla. Cook until mixture thickens again. Set aside.
2 cups Crushed Chocolate Sandwich Cookies (chocolate cookie part only plus more to garnish) 1/4 cup Butter (softened)
To Build Pie: Preheat oven to 350°. In a small bowl, combine the crushed chocolate sandwich cookies with the butter until thoroughly mixed. Press into a lightly greased springform pan. Bake for 15 minutes to set the crust.
Scrape brownie batter into the chocolate crust, forming an even layer. Bake for 20 minutes or until a toothpick comes out somewhat clean. Allow to cool slightly, and then pour pudding over the brownie layer, spreading into an even layer.
2 cups Heavy Cream 1 teaspoon Vanilla
Combine the heavy cream and vanilla and whip until peaks form, and use to top the chocolate pudding layer. Garnish with more crushed chocolate sandwich cookies.