Perfect for the chocolate lover in your life, this Mississippi mud cake is gooey, moist, and full of chocolate flavor. Everyone will be reaching for a second slice of this tender cake!
Preheat the oven to 350°F. Spray a 9x13-inch baking pan with baking spray.
In a medium bowl, whisk together the flour, cocoa, baking powder, salt, and baking soda.
In a large mixing bowl, whisk together the sugar, oil, milk, eggs, and vanilla. Add the flour mixture to the sugar mixture and stir until well combined and smooth. Pour the batter into the prepared cake pan.
Bake for 30 to 35 minutes or until the center of the cake is springy to the touch.
Meanwhile, after the cake has been baking for 15 minutes, make the icing.
For the Icing:
In a medium saucepan, melt the butter over medium-low heat. Whisk in the cocoa powder and milk until smooth. Add the powdered sugar and vanilla, and whisk until smooth. Remove from the heat and keep warm.
For the Assembly:
Remove the cake from the oven and immediately top with marshmallows and pecans. Drizzle the icing over the marshmallows and pecans. Let the cake cool completely before serving.
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Notes
The cake will have the texture of a fudgy brownie. It will puff around the sides but will fall a little during cooling.
If you're not a fan of pecans, you can swap them for walnuts.
Make sure to use room temperature ingredients so the ingredients mix smoothly into the batter. Overmixing the batter will lead to a tough, dry, and dense cake.
I highly recommend using a scale to measure your flour as it's the most accurate method and will prevent you from ending up with a dense cake. If you don't have a scale, fluff your flour with a spoon and spoon it into your cups before leveling it off with a knife. This method prevents you from overpacking the measuring cup.
Similarly, use a scale to measure the powdered sugar for the icing, as you do not want the icing to be too thick. If you add too much powdered sugar, your icing will be more like frosting and won't drizzle the cake over as smoothly.
As this Mississippi mud cake is a fudgy brownie-like texture, you must allow for it to cool before slicing into it. This ensures you get perfectly clean slices and that they hold their shape.
If you only have jumbo marshmallows, you can cut them into smaller pieces to mimic mini marshmallows.