Melt the butter and chopped chocolate in a small saucepan over medium-low heat.

Stir frequently until the mixture is smooth.

Set aside and let cool for about 10 minutes.

Meanwhile, whisk together the flour, cocoa powder, and salt.

Set aside.

Whisk the sugar into the chocolate mixture.

Then, add the eggs one at a time, whisking until combined after each addition.

Add vanilla and stir to combine.

Fold in the flour mixture using a rubber spatula. Batter will be thick.

Set aside.

Using an electric mixer, beat the cream cheese on medium-high spead until smooth.

Add the peanut butter, vanilla, salt, and sugar and mix until combined.

Add beaten egg and mix until just incorporated.

Preheat the oven to 350 degrees Fahrenheit and line an 8x8 baking dish with parchment paper.

Pour approximately 2/3 of the brownie batter into the bottom of the prepared baking dish and smooth with a rubber spatula.

Layer whole Oreos on top. It will take 16 Oreos to cover the entire brownie layer.

Cover with the cheesecake batter and smooth it with a spatula.

Scoop the remaining brownie batter on top and spread it out gently. Swirl slightly with a sharp knife, if desired.

Top with chopped Oreos.

Bake at 350 degrees for 40-45 minutes. Cheesecake will be golden brown and middle should only be just slightly jiggly.