Preheat oven to 375 degrees F. In a medium bowl stir together crushed cookies and the melted butter; press onto the bottom and up the sides of a 9-inch pie plate. Bake about 8 minutes or until firm. Cool completely on a wire rack.
In a medium saucepan combine sugar and cornstarch. Gradually stir in half-and-half. Cook over medium-high heat until thickened and bubbly, stirring constantly; reduce heat. Cook and stir for 2 minutes more. Remove from heat. Gradually stir about 1 cup of the hot filling into the egg yolks. Add yolk mixture to saucepan. Bring to a gentle boil, stirring constantly; reduce heat. Cook and stir for 2 minutes more. Remove from heat. Stir in the 1 tablespoon butter and the vanilla.
Immediately pour half of the hot mixture into a medium bowl; add chocolate pieces. Add peanut butter pieces to the remaining half of the hot mixture. Stir each mixture until melted and smooth. Pour warm chocolate mixture into piecrust; smooth top. Carefully and gently, spoon warm peanut butter mixture over chocolate mixture; smooth top. Gently press a sheet of plastic wrap directly onto the peanut butter filling. Chill for at least 4 hours.
Just before serving, spread Peanut Brittle Whipped Cream evenly over pie. Serve immediately.
Peanut Brittle Whipped Cream
In a large mixing bowl beat whipping cream with an electric mixer on medium to high speed until soft peaks form (tips curl). Reduce speed to low; beat in powdered sugar. Increase speed to medium-high and continue beating until stiff peaks form (tips stand straight). Gently fold in coarsely crushed peanut brittle candy.