Line an 8×8 inch (20×20cm) light-colored aluminum baking pan with parchment paper leaving a 2-inch overhang on two sides, lightly grease the two unlined sides, and set aside.

In a medium heavy-bottomed saucepan over the lowest heat, melt the 198g unsalted butter and 200g finely chopped bittersweet chocolate together, stirring constantly with a silicone spatula until completely smooth, then remove from heat and pour into a large mixing bowl to cool to below 90°F (32°C), approximately 10 to 15 minutes.

Whisk the 200g granulated white sugar into the cooled chocolate mixture vigorously for 60 full seconds, then add the 3 room-temperature eggs one at a time whisking fully after each addition, then add the 1 teaspoon pure vanilla extract and whisk to combine.

Switch to a silicone spatula and add the 60g all-purpose flour, 12g Dutch-process cocoa powder, and 1.5g fine sea salt all at once, then fold with slow strokes from the bottom of the bowl upward — maximum 20 strokes — until no flour streaks remain.

Reserve 3 tablespoons (45ml) of brownie batter in a small bowl, then pour the remaining batter into the prepared pan and spread into an even layer using an offset spatula.

In a medium bowl, beat the 226g room-temperature full-fat block cream cheese alone on medium speed for 90 seconds until completely smooth, scrape the bowl, then beat 30 seconds more.

Add the 50g granulated white sugar and beat on medium speed for 60 seconds scraping halfway through, then add the 1 room-temperature egg and beat on low speed for 20 seconds until just incorporated, then add the 1 teaspoon pure vanilla extract and beat on low for 10 seconds.

Preheat the oven to 325°F (163°C) and position the rack in the middle of the oven.

Pour the cheesecake batter evenly over the brownie base and spread into a smooth layer covering the brownie base completely edge to edge.

Press approximately 4 oz (113g) of the fresh raspberries individually into the cheesecake layer at varied depths — some flush to the surface, some pressed nearly to the brownie base — distributing them evenly across the pan.

Drop the reserved brownie batter in 8 to 10 small spoonfuls across the cheesecake surface, then drag a skewer through the drops in slow S-curves — 6 to 8 passes — to create the swirl pattern.

Bake on the middle rack at 325°F (163°C) for 33 to 38 minutes until the cheesecake edges look matte and set, the chocolate sections show a paper-thin crackled crust, and the center 2-inch circle still has a gentle unified wobble when the pan is nudged — do not wait for the center to look fully set.

Set the pan on a wire rack and cool at room temperature undisturbed for 1 full hour, then transfer uncovered to the refrigerator for a minimum of 4 hours or overnight.

Lift the slab from the pan using the parchment overhang, place on a cutting board, and slice into a 4×4 grid for 16 bars using a sharp knife wiped completely clean between every cut.

Add the remaining fresh raspberries and mint sprigs as garnish directly before serving.