Preheat your oven to 350°F (177°C). Line a 9x13-inch baking pan with parchment paper, allowing some overhang for easy removal. Lightly grease the paper.

In a large mixing bowl, whisk together the melted butter and sugar until smooth. Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

Sift the flour, cocoa powder, and salt into the wet ingredients. Mix until just combined; avoid overmixing.

Spread the brownie batter evenly in the prepared pan. Bake for 20-22 minutes, or until the surface is set but not fully cooked through.

Using a stand mixer or hand mixer, beat the softened cream cheese and sour cream until creamy and lump-free.

Gradually add the sugar and vanilla extract, beating until smooth.

Incorporate the eggs one at a time, mixing at a low speed to prevent over-aeration. scrape the sides of the bowl to ensure everything is well incorporated.

Carefully pour the cheesecake batter over the baked brownie layer, spreading it into an even layer.

Bake at 350°F (177°C) for 25-30 minutes, or until the edges of the cheesecake are set but the center still has a slight jiggle.

Remove from the oven and cool to room temperature. Refrigerate for at least 3-4 hours, or until completely chilled.

Once chilled, slice into squares. If desired, drizzle melted chocolate over the top for an extra touch of decadence.

Serve cold and watch them disappear!