Preheat the oven to 325°F. Adjust the oven rack to the center of the oven. Lightly spray a 13x9-inch cake pan with nonstick cooking spray. Set it aside.

Make the sponge cake: In a medium bowl, whisk the sugar, flour, baking soda, salt, and espresso, making sure to break any clumps, and set aside. In a medium saucepan set over low heat, combine the milk, chocolate, and cocoa powder. Stir constantly until the chocolate melts and the mixture looks like a rich chocolate sauce. Remove from heat and let cool slightly. Then, whisk in the oil, eggs, and vanilla. Do not worry if it looks a little bit curdled at first—the oil will try to separate from the batter, but the eggs will emulsify and make it smooth. Continue whisking until it looks smooth. Use a rubber spatula to scrape the mixture onto the dry ingredients and combine well.

Bake the cake: Scrape the batter into the prepared cake pan. Gently tap the pan on your kitchen counter a few times to get rid of some air bubbles. Bake the cake for about 30 minutes, rotating the pan halfway through to ensure even baking. Insert a toothpick in the middle to check for doneness—the cake is ready when it comes out with a few crumbs stuck to it, but no wet batter. Place the cake pan on a wire rack to cool.

Meanwhile, make the milk mixture: While the cake bakes, make the tres leches mixture. In a small saucepan set over low heat, combine the sweetened condensed milk, heavy cream, evaporated milk, cocoa powder, and cinnamon. Whisk vigorously until the cocoa powder and cinnamon are fully dissolved, and the mixture is heated through. It will be frothy. Set it aside to cool.

Poke and bathe the cake: Poke the cake all over with a toothpick or a fork. It’s okay if the cake is still warm. Slowly pour the warm milk mixture evenly over the cake. Don’t worry if it looks like it is too much milk—it isn’t—the cake will quickly absorb all of it. Tightly cover the cake pan with plastic wrap and refrigerate it for at least an hour. You want the cake to be cold so that the whipped cream doesn’t melt off when you frost it.

Melt the chocolate: Fill a medium pot with about 2 inches of water. Set it over medium-high heat to bring the water to a gentle boil. Lower the heat to a simmer and set a medium heat-proof bowl on top of the pot. Make sure the boiling water is not touching the bottom of the bowl. This is called a double boiler. Add the chocolate chips and ⅓ cup heavy cream. Gently stir until the chocolate is fully melted. Set it aside to cool to room temperature. Milk chocolate will give you a sweeter, lighter cream that balances out the deep chocolate flavors of the cake. If you want even more chocolate flavor, opt for bittersweet.

Whisk the cream: In a medium bowl, whisk the remaining heavy cream until soft peaks start forming, being careful not to over-whip it. You can do this by hand with a whisk or with an electric handheld mixer. Then, gently whisk in the cooled melted chocolate until fully incorporated.

Decorate the cake: Use the back of a spoon or an offset spatula to spread the chocolate whipped cream over the chilled tres leches cake. Create small peaks and swirls, if you’d like. Garnish with your favorite berry, if you’d like—strawberries, raspberries, and maraschino cherries balance out the chocolate very nicely. I like to use the berries as a guide to indicate where to cut the portions. Another way to decorate the cake: Use a vegetable peeler to make chocolate curls. Simply run the blade over a bar of your favorite chocolate over a plate. Sprinkle them on the cake.

Serve the cake: Keep the cake chilled in the fridge until ready to serve. This cake tastes even better the day after you make it—the milk mixture would have had a chance to really soak through the cake. Leftovers (though there normally isn’t any) can be refrigerated for up to 3 days tightly covered with plastic wrap. It’s not suitable for freezing as it will turn rubbery, and the whipped cream will collapse. Did you love the recipe? Leave us stars below!