6 tablespoon(s) butter, melted, plus more for pan
1 1/2 cup(s) graham cracker crumbs
1/4 cup(s) finely crushed chocolate sandwich-cookie crumbs
1/4 cup(s) sugar
3/4 cup(s) creamy peanut butter
3 package(s) (8 ounces each) cream cheese, at room temperature
1 cup(s) sugar
1 cup(s) sour cream
1 1/2 teaspoon(s) vanilla extract
3 (large) eggs, lightly beaten
1 cup(s) hot fudge ice cream topping
Peanut butter cups, cut into halves, for garnish
Crust: Preheat oven to 350 degrees F. Brush 9-inch springform pan with melted butter. In large bowl, mix all crumbs, sugar, and 6 tablespoons butter. Press onto bottom and 1 inch up side of pan. Bake 10 minutes or until crust has set. Cool completely on wire rack. In small bowl, microwave peanut butter on high 30 seconds or until melted. Brush onto bottom crust.
Cheesecake: In large bowl, with mixer on medium speed, beat cream cheese and sugar until smooth, about 3 minutes, scraping bowl with rubber spatula as needed. Beat in sour cream and vanilla. Reduce speed to low. Beat in eggs until just combined. Remove 1 cup batter; set aside. Pour remaining batter into prepared crust.
In small bowl, microwave 1/4 cup hot fudge topping on high 30 seconds or until pourable; fold into reserved 1 cup batter. Carefully pour chocolate filling over batter in pan; swirl with knife.
Place springform pan, inside roasting pan, on rack in oven; carefully fill roasting pan with boiling water to come halfway up side of springform pan. Bake until set around edges but slightly wobbly in center, about 55 minutes. Turn oven off. Remove pan from water bath. Return cake to oven and let cool inside, with door propped open slightly, 2 hours. Transfer pan to wire rack.
In small bowl, microwave remaining 3/4 cup hot fudge topping on high 30 seconds or until pourable. Spread over top of cake with offset (angled) spatula; let cool. Garnish with peanut butter cups. Cover and refrigerate at least 6 hours or until well-chilled, up to 3 days. To serve, remove side of pan.