Preheat the oven to 350°F (177°C). Line a 9×13-inch pan with parchment paper for easy removal.

In a food processor, pulse the Oreos into fine crumbs. Mix the crumbs with melted butter until combined. Press this mixture firmly into the bottom of the prepared pan. Pre-bake the crust for 10 minutes.

In a large mixing bowl, beat the softened cream cheese and granulated sugar together until smooth and creamy. Add in sour cream, peanut butter, vanilla extract, and salt. Mix until well combined.

Add the eggs one at a time, mixing well after each addition.

Pour the peanut butter filling over the warm Oreo crust. Bake for 35–38 minutes until the center is set but still slightly jiggly.

Let the cheesecake cool at room temperature for 1 hour, then refrigerate for 3–4 hours until completely chilled.

In a small saucepan, melt the butter and chocolate chips together over low heat, stirring until smooth. Let it cool slightly.

Spread the melted chocolate mixture evenly over the chilled cheesecake bars. Refrigerate for an additional 45–60 minutes until set.

Lift the bars out of the pan using the parchment paper and cut into squares.