For the brownies:
14 tbsp. unsalted butter
6 oz. bittersweet chocolate, coarsely chopped
1 cup cocoa powder (I used Hershey’s Special Dark)
2 cups sugar
6 oz. cream cheese, softened
6 large eggs
2 tsp. vanilla extract
½ tsp. salt
1 cup all-purpose flour
For the peanut butter cheesecake swirl:
8 oz. cream cheese, at room temperature
2/3 cup creamy peanut butter
6 tbsp. sugar
1 large egg
1 tsp. vanilla extract
Preheat the oven to 350˚ F. Line a 9 x 13-inch baking pan with foil and spray lightly with cooking spray. To make the brownie batter, combine the butter and chocolate in a large heatproof bowl set over simmering water. Heat, stirring occasionally, until the mixture is completely melted and smooth. Remove the bowl from the heat. Whisk in the cocoa powder, sugar, eggs and cream cheese until smooth and well blended. Mix in the vanilla and salt. Add the flour to the bowl and whisk just until incorporated. Pour the brownie batter into the prepared baking dish and smooth the top with a spatula.
To make the peanut butter cheesecake portion, combine the cream cheese, peanut butter and sugar in the bowl of an electric mixer. Beat on medium-high speed until completely smooth, about 2-3 minutes. Blend in the egg and vanilla until incorporated, scraping down the bowl as needed.
Drop spoonfuls of the peanut butter mixture over the brownie batter in the pan, creating a cobblestone appearance. Use a knife or wooden skewer to gently swirl together the peanut butter mixture and brownie batter. Bake 30-35 minutes, until the center is just set. Transfer to a wire rack and let cool to room temperature. Cover and refrigerate until well chilled before slicing and serving.