01 -
Heat the oven to 325°F. Line an 8-inch square baking pan with parchment paper, leaving overhang on two sides for lifting the brownies out later.
02 -
Combine blackberries, sugar, water, and lemon juice in a small saucepan over medium heat. Simmer for 8-10 minutes, mashing the berries, until glossy and slightly thick. Strain for a smooth sauce if desired, then cool.
03 -
Whisk melted butter, granulated sugar, brown sugar, eggs, vanilla, and salt until smooth. Fold in cocoa powder and flour just until combined, then stir in the chocolate chips.
04 -
Spread the brownie batter evenly in the prepared pan, pushing it into the corners with a spatula.
05 -
Beat softened cream cheese and sugar until smooth. Mix in sour cream, egg, vanilla, and salt until creamy, scraping the bowl as needed.
06 -
Spread the cheesecake mixture over the brownie batter. Dot the cooled blackberry puree over the top and drag a thin knife through the dots a few times to make loose swirls.
07 -
Bake for 45-52 minutes, until the edges are set and the center has only a slight wobble. A toothpick inserted into the brownie layer should come out with moist crumbs.
08 -
Cool at room temperature for 1 hour, then refrigerate for at least 2 hours. Lift from the pan and cut into 16 squares with a warm, wiped knife.