Upside-Down Chocolate Cake

This chocolate cake plays a magic trick in the oven. Mini marshmallows go in the bottom of the pan, followed by a stirred cocoa-and-hot-water syrup, then chopped walnuts, then a layer of boxed devil’s food batter on top. During the bake, everything swaps places. The marshmallows melt down through the cake, the cocoa syrup pulls upward as the batter sets, and what bakes out is a chocolate cake floating on a slick of marshmallow-walnut-cocoa goo.

This is a self-saucing cake, similar in concept to a British pudding cake. The hot cocoa water below the batter stays liquid because it’s denser than the cake. As the cake rises and seals, the liquid layer beneath becomes a sauce.

The boxed mix is a feature, not a shortcut. Devil’s food cake mixes are formulated with extra leavening to rise dramatically, which is exactly what you need to seal the top while the bottom turns to chocolate sauce.

Flip onto a serving platter while warm. Cooled, the sauce thickens and the inversion gets messy.

Kitchen Tips

• Don’t skip toasting the walnuts on a dry sheet pan for 5 to 7 minutes before adding. Raw walnuts taste flat under the cake; toasted ones perfume the syrup.
• Use a 13×9 pan that’s at least 2 inches deep. The marshmallow and cocoa layer rises during baking and will overflow a shallow pan.
• Serve warm with a scoop of vanilla ice cream. The contrast of cold cream against hot chocolate sauce is the whole point.

Variations

• Swap walnuts for pecans and add 1 teaspoon of cinnamon to the cocoa mixture for a Mexican-leaning cake.
• Use a German chocolate mix instead of devil’s food for a coconut-caramel angle.
• Drop in chunks of dark chocolate along with the marshmallows for double-melt pockets.