01 -
Heat your oven to 350°F (175°C). Put parchment paper in an 8×8-inch baking dish with extra hanging over the sides so you can lift it out later.
02 -
Put the butter and dark chocolate in a bowl that's safe for the microwave. Heat it in 30-second bursts, stirring each time, until it's all melted and looks smooth. Let it cool a bit.
03 -
Stir both sugars into your chocolate mixture until they're completely mixed in. Add eggs one by one, mixing well after each one goes in.
04 -
Sift the flour and cocoa powder together. Fold them gently into the chocolate mix with a spatula just until you can't see any dry spots. Add the vanilla extract and stir.
05 -
In another bowl, beat the soft cream cheese and sugar until it's creamy with no lumps. Mix in the egg, then add the heavy cream and vanilla, beating until everything's blended well.
06 -
Spread the brownie mix evenly in your lined pan. Gently pour the cheesecake mixture on top of the brownie layer.
07 -
If you want, grab a knife or toothpick and swirl through both layers to make pretty marble patterns in your cake.
08 -
Pop it in the oven for 35 to 40 minutes. You'll know it's done when the edges are firm but the middle still jiggles a tiny bit. Don't cook it too long or it'll dry out.
09 -
Let the whole thing cool down to room temperature. Then stick it in the fridge for at least 2 hours, though overnight works even better for slicing.
10 -
Grab the parchment paper edges to lift the cake out. Cut it into squares and serve it cold. If you want, top with some melted chocolate or add whipped cream and berries.