For Crust: Position rack in center of oven and preheat to 350° degrees. Butter 9 inch spring form pan. Mix chocolate cookie crumbs, chopped peanuts, melted butter, brown sugar and pinch of salt in bowl until well combined. Press mixture evenly onto bottom and sides of pan. A little oil on your fingers helps to keep the crust from sticking to your fingers. Bake until set, about 8 minutes. Set aside to cool. Reduce oven to 325° degrees.
For Filling: Using electric mixer, beat cream cheese and brown sugar in large bowl until smooth. Add peanut butter and vanilla extract and beat just until blended. Add eggs 1 at a time, beating just until blended after each addition. Add whipping cream and beat until smooth. Stir in peanut butter cup pieces.
Pour filling into crust. Bake until sides of cake are set, but center still moves slightly, about 55 minutes. Cool cake in pan.
For Topping: Place all ingredients in microwavable bowl and heat at 50% power for 30 seconds. Stir. Continue to heat at 10 second intervals until chocolate is barely melted. Do Not Overheat. Stir until smooth and pour over top of cheesecake, spreading chocolate to edges.
Cover and refrigerate overnight. Serve your Peanut Butter Cup Cheesecake.