9 ounces chocolate wafers chocolate or other cookie
6 ounces chocolate bitter- or semisweet, coarsely chopped or chips
0.5 cups dark brown sugar
7 tablespoons unsalted butter melted and still hot
1 cups cream heavy or whipping
13 ounces chocolate bittersweet or semisweet, chopped
2 tablespoons smooth peanut butter optional
16 ounces cream cheese room temperature
1.25 cups smooth peanut butter
1 cups granulated sugar
0.75 cups sour cream
3 units large eggs
2 teaspoons vanilla extract
0.33 cups cream heavy or whipping
4.5 ounces chocolate bittersweet or semisweet, chopped
1 tablespoon smooth peanut butter optional
Equipment
springform pan
food processor
large saucepan
electric mixer
roasting pan
small saucepan
Directions
Double-wrap outside of a 9-inch springform with 3-inch high sides with aluminum foil (heavy-duty if possible). In a food processor, blend cookies, chopped chocolate and brown sugar until finely ground. Drizzle in melted butter and process until crumbs stick together, scraping the bowl as needed. Transfer crumbs to prepared pan and press crumb mixture up the sides to within 1/2 inch of the top, then evenly over the bottom of the pan. Chill crust until the next step.
Bring cream to a simmer in a large saucepan. Remove from heat; whisk in chocolate and peanut butter (if using) until smooth. Pour into the bottom of the chilled crust and spread in an even layer. Freeze until firm, about 30 minutes.
Preheat oven to 325°F.
Using an electric mixer, beat cream cheese, peanut butter, and sugar in a large bowl until well-blended and fluffy. Beat in sour cream, then eggs one at a time, and vanilla. Mix until smooth. Pour over the fudge layer that has set in the freezer.
Place foil-wrapped springform pan in a roasting pan large enough to hold it. Fill the roasting pan with enough hot water to come 1-inch up the sides of the springform and carefully transfer to the middle oven rack. Alternatively, place springform on middle baking rack if not using a water bath.
Bake the cake until slightly firm to the touch and the top appears dry, about 75 to 90 minutes. The center two inches should only move slightly when the pan is gently shaken. Transfer cheesecake to the fridge until fully cool, at least three hours.
Heat cream in a small saucepan until simmering. Off the heat, whisk in chocolate and peanut butter (if using). Pour onto chilled cheesecake and spread to the edges. Return cheesecake to the fridge until the ganache sets, about 30 minutes.
Gently cut around the edge of the cheesecake crust and springform pan to make sure it isn’t sticking. Unhinge the sides. Serve in very skinny wedges. Cake keeps in the fridge for up to a week, and longer in the freezer.