This rich cake is easy to whip up at the last minute.

Makes one 8-inch cake, about 12 servings

3/4 cup water
1/4 cup sugar
8 tablespoons (1 stick) unsalted butter
18 ounces milk chocolate, cut into 1/4-inch pieces
7 large eggs
2 tablespoons dark rum, or other liqueur
1 tablespoon grated orange zest

Chocolate shavings, for finishing

One 8-inch diameter x 2-inch deep round cake pan, buttered and the bottom lined with a disk of buttered parchment or wax paper, set inside a small roasting pan

  1. Set a rack in the middle level of the oven and preheat to 325 degrees.
  2. In a medium saucepan, combine the water and sugar. Place over medium heat and bring to a simmer, stirring occasionally to dissolve all the sugar crystals.
  3. Cut the butter into 8 pieces and add to the pan, continuing to cook over medium heat, stirring occasionally, until butter is melted. Remove pan from heat, add chocolate and swirl pan to submerge chocolate entirely. Allow to stand for 2 minutes to melt the chocolate.
  4. Meanwhile, whisk the eggs with the rum and orange zest in a large mixing bowl. Whisk the chocolate mixture smooth, then whisk it into the egg mixture.
  5. Pour the batter into the prepared pan and add warm water to a depth of 1 inch in the roasting pan. Set pan in oven and bake cake for about 1 hour, or until well risen and firm in the center.
  6. Remove roasting pan from oven and carefully remove cake pan, using a wide spatula to lift it out of the larger pan. Cool on a rack in the pan.
  7. Wrap and chill cake in pan. To unmold, set pan over low heat for a few seconds to melt butter between pan and paper lining. Insert a small, sharp paring knife between cake and side of pan and run knife around inside of pan to loosen cake. Invert cake to a platter and remove paper if stuck to cake. Sprinkle cake lightly with chocolate shavings.
  8. To serve, cut in thin wedges.

Storage: Store cake loosely covered at cool room temperature for up to 6 hours. Wrap and refrigerate leftovers. For advance preparation, wrap cake in pan and refrigerate 1 week or freeze for up to 1 month.