01 -
Preheat oven to 175°C. Line a 23 x 23 cm square pan with foil and lightly grease with nonstick spray for easy removal and clean edges.
02 -
Combine chopped unsweetened baking chocolate and unsalted butter in a large microwave-safe bowl. Heat in 30-second intervals, stirring between each, until melted and smooth. Let cool slightly.
03 -
Stir granulated sugar and cocoa powder into the melted chocolate mixture. Add eggs one by one, mixing well after each addition. Incorporate vanilla extract and sea salt. Gently fold in flour just until combined, avoiding overmixing.
04 -
Evenly spread the brownie batter into the prepared baking pan, smoothing the top with a spatula. Set aside.
05 -
In a separate bowl, beat softened cream cheese and sour cream with a hand mixer or stand mixer on medium speed until the texture is smooth and lump-free. Add eggs, granulated sugar, and vanilla extract, blending until creamy and completely combined.
06 -
Pour cheesecake mixture over the brownie batter. Using a butter knife or skewer, gently swirl the two batters to create a marbled effect, taking care not to overmix.
07 -
Place the pan in the preheated oven and bake for 50 to 55 minutes, until the top is set, lightly puffed, and no longer glossy. Edges should appear lightly golden.
08 -
Remove from oven and allow to cool completely at room temperature. Refrigerate for at least 4 hours until thoroughly chilled and set before slicing.
09 -
Slice into squares and serve chilled for optimal texture. Store in an airtight container in the refrigerator for up to 3 days, or wrap bars individually and freeze for up to 3 months.