This dense, luscious cake has a texture a little like fudge and a little like cheesecake. A small slice goes a long way. Serves sixteen Yields one 9-1/2 inch cake

ingredients
For the vanilla batter:
8 ounces cream cheese, softened to room temperature
2/3 cup granulated sugar
1 large egg
1 teaspoon pure vanilla extract

For the chocolate batter:
10 ounces bittersweet chocolate, finely chopped
5 ounces (10 tablespoons) unsalted butter, cut into 6 pieces
3 large eggs
1/3 cup granulated sugar
1 tablespoon dark rum or espresso
1 teaspoon pure vanilla extract
Pinch table salt

Cocoa powder for dusting

Position an oven rack in the middle of the oven and heat the oven to 300°F. Lightly grease a 9×2-inch round cake pan and line the bottom with parchment.

Make the vanilla batter: In a medium bowl, beat the softened cream cheese with an electric mixer until smooth. Add the sugar and continue beating until well blended and no lumps remain. Add the egg and vanilla and beat just until blended. Set aside.

Make the chocolate batter: In a medium bowl, melt the chocolate and butter in a large metal bowl over a pan of simmering water or in the microwave. Whisk until smooth and set aside to cool slightly. With a stand mixer fitted with the whip attachment (or with a hand mixer), beat the eggs, sugar, rum or espresso, vanilla, and salt on medium high until the mixture is pale and thick, 3 to 4 minutes. With the mixer on low, gradually pour in the chocolate mixture and continue beating until well blended.

Combine and bake: Spread about half of the chocolate batter in the bottom of the pan. Alternately add large scoopfuls of each of the remaining batters to the cake pan. Using a knife or the tip of a rubber spatula, gently swirl the two batters together so they’re mixed but not completely blended. Rap the pan against the countertop several times to settle the batters.

Sprinkle cocoa on the bottom of the cake before inverting it onto another plate; the cocoa will keep the cake from sticking when you slice and serve it.

Bake until a pick inserted about 2 inches from the edge comes out gooey but not liquid, 40 to 42 minutes; don’t overbake. The top will be puffed and slightly cracked, especially around the edges. It will sink down as it cools. Let cool on a rack until just slightly warm, about 1-1/2 hours. Loosen the cake from the pan by holding the pan almost perpendicular to the counter; tap the pan on the counter while rotating it clockwise. Invert onto a large flat plate or board. Remove the pan and carefully peel off the parchment. Sift some cocoa powder over the cake (this will make it easier to remove the slices when serving). Invert again onto a similar plate so that the top side is up. Let cool completely. Cover and refrigerate until very cold, at least 4 hours or overnight, or freeze
To slice the marble cake neatly, use a hot knife (run it under hot running water and dry it). Wipe the blade clean between slices