6. Place the baking sheet with the trays into the preheated oven. Bake for 25–30 minutes, or until the edges are set and a toothpick inserted near the center comes out with moist crumbs but not wet batter. This dessert is meant to be soft and a bit pudding-like, so don’t overbake.
7. Remove the trays from the oven and let them cool on a wire rack for at least 15–20 minutes. The dessert will continue to set as it cools but should stay soft and spoonable.
8. Serve warm, scooped straight from the foil trays into bowls. Cover any leftovers tightly with foil and store at room temperature for a day, or in the refrigerator for up to 3 days. Rewarm gently in a low oven if you like it served warm again.
If you’d like a deeper coffee flavor, replace half of the milk with additional brewed coffee, or stir 1–2 teaspoons of instant espresso powder into the dry ingredients before adding the liquids. For a milder, more kid-friendly version, use all milk and no coffee and simply call it a chocolate pudding bake. You can also swap in a devil’s food or dark chocolate cake mix for a richer taste, or try a yellow cake mix for a lighter, mocha-swirled effect. Stir a handful of chopped nuts—such as walnuts or pecans—into the batter for a bit of crunch, or sprinkle them over the top along with the chocolate chips. If you’re cooking for a crowd, this recipe doubles easily and can be baked in larger disposable trays; just watch the baking time and test the center for doneness. To dress it up for a special occasion, dust the cooled top lightly with powdered sugar or cocoa, or serve each portion with a drizzle of chocolate or caramel sauce. For make-ahead convenience, bake both trays, cool completely, wrap one well in foil, and freeze for up to a month; thaw overnight in the refrigerator and warm gently before serving.