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Dripping iced chocolate cake squares on metal pan.

Gooey Chocolate Sheet Cake

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5 from 1 review

An old-fashioned sheet cake with great chocolate flavor. The top layer is crackly outside but remains gooey and rather soft inside. It keeps well and is perfect for potlucks, casual parties, or when you simply crave chocolate! Have it slightly underbaked for a fudgier experience. 

  • Total Time: 40 minutes
  • Yield: 12 servings



For the cake:

  • 1 cup unsalted butter
  • 1/2 cup unsweetened cocoa powder
  • 1 cup of water
  • 2 cups all-purpose flour or cake flour
  • 1 1/2 cups firmly packed brown sugar, light or dark
  • 1 teaspoon baking soda
  • 1 teaspoon cinnamon
  • 1/2 teaspoon salt
  • 1 14-oz can sweetened condensed milk, divided
  • 2 eggs, at room temperature
  • 1 teaspoon vanilla extract

For the frosting:

  • 1/4 cup butter
  • 2 tablespoons unsweetened cocoa powder
  • 1 cup powdered sugar (also known as icing sugar or confectioners' sugar)


  1. Preheat the oven to 350ºF/180°C.
  2. Grease a 13x18-inch pan. I serve it directly from the pan or cake tin, but if you want to remove it and serve it on a platter, you can line the sheet pan with a piece of parchment paper. Take a strip wide as the long side of the pan and place it covering the bottom and the two long sides. This way, it'll be easier to remove the cake by lifting the paper on both sides. 

For the cake:

  1. Melt 1 cup of butter in a small saucepan.
  2. Add cocoa and water and bring to a boil. Remove from heat.
  3. Sift flour, baking soda, cinnamon, and salt in a large mixing bowl. Add the brown sugar and combine. 
  4. Make a well in the center and add the cocoa mixture, 1/3 can (eyeball it) of the condensed milk, the eggs, and vanilla. Mix until the batter is smooth.
  5. Pour into the prepared pan and bake for about 20 minutes, until the cake springs back and a cake tester or toothpick inserted in the center comes out with some moist crumbs attached. It should not come out wet. Don't overbake it. This is not a very tall cake so it doesn't take long to bake. But all ovens are different so check to see if it's done. 

For the frosting:

Have it ready before the cake comes out of the oven.

  1. Melt the remaining ¼ cup of butter in a small saucepan (I use the same one as before without cleaning it).
  2. Remove from heat and add the 2 tablespoons of cocoa powder, and the rest of the condensed milk. Mix well.
  3. Add the powdered sugar and mix until completely smooth.
  4. Spread over the warm chocolate cake as it comes out of the oven. You can poke holes with a toothpick or brochette stick so it seeps deeper. 
  5. Let cool completely.
  6. If removing it from the pan, refrigerate it first until firm so it's easier to remove. 
  7. Refrigerate leftovers, well covered in plastic wrap or in an airtight container. 


  • Organization: read the recipe first and make sure you have ingredients at the right temperatures, equipment needed, and enough workspace. This will make the process so much easier!
  • Baking time: keep in mind that all ovens and pans are different, even if they look the same or very similar. The baking time in my recipes is as accurate as it can be, but it might take you more or less time. Use a thermometer inside the oven (like the OXO oven thermometer) to check that the temperature is right. I recommend you keep track of how your oven works and what tiny details you might need to adjust. 
  • Icing or glaze: always pour it over the warm cake so it seeps a little into the top of the cake. Or make a poke cake: pierce or poke holes with a brochette stick or toothpick on the surface of the cake when it comes out of the oven. Then pour the chocolate icing over them. It will seep more into the baked cake and the whole thing will be fudgier. 
  • Cake pan: I use a rectangular pan without a removable bottom and serve the cake straight from the pan. This is because when you pour the frosting some of it goes to the sides, and spills down the bottom sometimes. But you can use a pan with removable bottom, refrigerate the cake after you glaze it and then remove it before serving.
  • Fudgier cake: if you slightly underbake the cake, it will be fudgier. And even more amazing in my opinion!
  • Walnuts: sometimes, I sprinkle chopped walnuts on top of the icing before it sets. 
  • Serving it: I like it as is, straight from the pan. But you can recreate the so-called 'better than sex cake' by adding a thick layer of whipped cream (or cool whip topping), drizzling caramel sauce or dulce de leche over it, and adding chopped heath bars or toffee bits on top. A decadent dessert for those with a sweet tooth!
  • Variation: for a more sophisticated version, add a tablespoon of your favorite liquor (I love Kahlua, Baileys, and Cointreau) to the batter and the icing. Or whisky/bourbon; it works so well with chocolate. Did I tell you about my favorite cake, the Bourbon Hot Chocolate Bundt Cake?
  • Cocoa powder: always use unsweetened cocoa powder. I like Hershey's unsweetened cocoa powder, Ghirardelli Premium baking cocoa, and Scharffen Berger natural cocoa powder. In my experience, the dark ones are the best (this does not apply to the super dark used for making homemade oreo cookies known as 'dark cocoa powder').
  • Sweetened condensed milk: it's a must ingredient and can't be substituted. Use the regular type such as Carnation condensed milk or Eagle Brand sweetened condensed milk, not unsweetened or evaporated milk.
  • Powdered sugar: also called icing sugar or confectioners' sugar, it's powder-like and needed to create that crackly top. A popular brand is Domino confectioner sugar.
  • Vanilla: I use pure vanilla extract or pure vanilla paste when available, but a good vanilla essence (artificially flavored) also works. 
  • Author: Paula Montenegro
  • Prep Time: 20 minutes
  • Cook Time: 20 minutes
  • Category: Cakes
  • Method: Baking
  • Cuisine: American