Preheat your oven to 350°F. In a large mixing bowl, combine the melted butter with granulated sugar and brown sugar. Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract. Gradually fold in the flour, cocoa powder, and salt until just combined. Pour the brownie batter into a greased and floured 9-inch round cake pan.

In another bowl, beat the cream cheese until smooth using an electric mixer. Add in the cookie butter and granulated sugar, beating until well incorporated. Mix in the eggs one at a time, followed by the vanilla extract, until smooth and creamy.

Pour the cheesecake mixture over the brownie layer. Use a knife to create swirls by dragging through the layers, creating a marbled effect.

Bake in the preheated oven for 45 to 50 minutes, or until the cheesecake layer is set and a toothpick inserted into the center comes out with just a few moist crumbs.

Allow the brownies to cool completely in the pan on a wire rack. Slice into wedges to serve. Pair with your favorite beverage for a delightful treat.

Store leftovers in an airtight container at room temperature for up to 3 days, or refrigerate for up to a week. For longer storage, freeze for up to 3 months.