Preheat your oven to 350°F (175°C). In a medium saucepan, melt the dark chocolate and butter over low heat, stirring until smooth, about 5-7 minutes.

In a large mixing bowl, combine the melted chocolate mixture with sugar and eggs, whisking until blended. Fold in flour until just combined.

In a separate bowl, beat the cream cheese until smooth. Gradually add caster sugar, then egg and vanilla, mixing just until combined.

Prepare an 8x8-inch baking dish by lining with parchment paper. Pour brownie batter into the dish, then dollop cheesecake filling on top and gently swirl.

Bake for 25-30 minutes until edges are set but the center remains slightly soft. Allow to cool in the pan for 15-20 minutes.

Lift brownies out using parchment paper and slice into squares. Enjoy!