Mutti’s Marble Cake
¼ cup unsweetened cocoa
3 tablespoons milk
1 2/3 cups white sugar, divided
1 cup unsalted butter, softened
4 large eggs
Grated zest of 1 lemon
¼ cup light rum
1 teaspoon vanilla extract
2 ¼ cups white flour
1-tablespoon baking powder
½ cup warm milk
1/3 cup semisweet chocolate chips
Preheat the oven to 350°F. Warm the cocoa, milk, and ¾ cup sugar together to dissolve the cocoa and sugar. Set Aside.
Using an electric mixer, beat together the butter and the remaining sugar until light and fluffy, about 3 minutes. Add the eggs, one at a time, beating after each addition, followed by the lemon zest, rum, vanilla, and salt. The mixture may look curdled at this point.
Sift the flour and baking powder together and, with the rubber spatula, quickly stir into the egg mixture, in the three batches, alternation with the ½ cup warm milk, beating only enough to combine after each addition. Please do not over beat the batter or the cake will be tough.
Divide the batter and add the cocoa mixture to one-third, along with the chocolate chips, stirring just enough to combine.
Fill a buttered and floured 9- by 5 inch loaf pan with three alternating layers of the two batters, starting and ending with the white. Use a knife to swirl the batters together. Resist over blending. You can make a wide W to create a marbled effect.
Bake for 75 to 80 minutes, until the cake tests done. Cool on a rack for 10 minutes, then gently unmold the cake. Let cool for at least 1 hour, or even better, overnight, before cutting. A serrated knife works best.