Preheat the oven to 350°F (175°C) and combine graham cracker crumbs, melted butter, sugar, and salt in a bowl. Press the mixture into a 9-inch springform pan and bake for 10-12 minutes until lightly golden. Let cool slightly on a wire rack, then reduce oven temperature to 325°F (160°C).

In a large bowl, beat the softened cream cheese with an electric mixer until smooth and creamy. Gradually beat in the creamy peanut butter until fully incorporated.

Whisk together granulated sugar, flour, and salt in a separate small bowl. Gradually add this dry mixture to the cream cheese mixture, beating on low speed until just combined.

Mix in the vanilla extract, then add eggs one at a time, beating on low speed until the yolk disappears. Gently fold in the heavy cream until just combined.

Wrap the outside of your springform pan tightly with several layers of heavy-duty aluminum foil to prevent water seepage. Pour the cheesecake filling over the cooled crust.

Place the foil-wrapped springform pan into a larger roasting pan. Carefully pour hot water into the roasting pan until it comes about halfway up the sides of the springform pan.

Bake for 60-70 minutes, or until the edges are set but the center still jiggles slightly. Turn off the oven, crack the door, and leave the cheesecake in the water bath for 1 hour to cool slowly.

Remove the cheesecake from the water bath, carefully remove the foil, and let it cool completely on a wire rack at room temperature for 1-2 hours.

Once completely cool, cover loosely with plastic wrap and refrigerate for at least 6-8 hours, or preferably overnight, to allow it to fully set.

If using, whisk together the peanut butter, heavy cream, and powdered sugar in a small bowl until smooth. Add milk, a tablespoon at a time, until it reaches a drizzling consistency.

Run a thin knife around the edge of the pan before releasing the springform. Drizzle with the peanut butter topping and garnish with chopped peanuts or mini chocolate chips, then slice and serve.