Preheat your oven to 350°F (175°C). Line a 9x9 inch baking dish with parchment paper, allowing some overhang for easy removal later.
In a food processor, crush the 36 Oreos until they turn into fine crumbs. In a mixing bowl, combine the Oreo crumbs with the melted salted butter. Stir until the mixture resembles wet sand. Press the mixture firmly into the bottom of the prepared baking dish to create an even crust. Bake for 10 minutes, then remove and let cool.
In a large mixing bowl, beat the softened cream cheese and creamy peanut butter together with an electric mixer until smooth and creamy. Gradually add in the granulated sugar, followed by the eggs one at a time, mixing well after each addition. Finally, stir in the vanilla extract until everything is well combined.
Pour the cheesecake filling over the cooled Oreo crust, spreading it evenly with a spatula. Bake in the preheated oven for 25-30 minutes, or until the edges are set and the center has a slight jiggle. Remove from the oven and let cool completely at room temperature. Then, refrigerate for at least 2 hours to firm up.
Once chilled, you can top your Cheesecake Peanut Butter Bars with whipped cream if desired. Slice into squares and serve chilled or at room temperature.
