Melt the bittersweet chocolate and butter together in a heatproof bowl over a simmering pot of water, stirring continuously until smooth and glossy. Remove from heat and let cool slightly.

In a large mixing bowl, beat together the sugar and eggs until light and fluffy, about 2-3 minutes. Blend in the cooled chocolate mix and add vanilla extract. Fold in the flour and salt until just combined.

Preheat oven to 180°C (350°F). Grease a baking pan with butter or non-stick spray. Pour the brownie batter into the prepared pan and bake for about 20 minutes until edges are set but center is soft.

Beat cream cheese in a separate bowl until smooth. Gradually add powdered sugar and lemon juice until fluffy.

Gently wash fresh raspberries or thaw and pat dry frozen ones. Fold into the cheesecake mixture carefully to maintain their shape.

Pour the cheesecake filling over the cooled brownie base. Lower the oven temperature to 160°C (320°F) and bake for an additional 30-35 minutes until edges are set but center has a slight jiggle.

After baking, turn off the oven and crack the door open to cool the cheesecake gradually inside for about an hour before chilling in the fridge for at least 4 hours or overnight.