Ingredients:

  • 1.5 cups all-purpose flour
  • 1.5 cups granulated sugar
  • 3/4 cup Dutch process cocoa powder (for cake)
  • 1 teaspoon baking soda
  • 1 teaspoon salt
  • 1 cup whole milk
  • 1/2 cup unsalted butter, melted (for cake)
  • 2 large eggs
  • 2 teaspoons vanilla extract (for cake)
  • 4 cups mini marshmallows
  • 1/3 cup unsalted butter, softened (for frosting)
  • 1/2 cup natural unsweetened cocoa powder (for frosting)
  • 2 cups powdered sugar
  • 1/4 cup whole milk (for frosting)
  • 1 teaspoon vanilla extract (for frosting)

Instructions:

  1. Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan. In a large bowl, whisk together the all-purpose flour, granulated sugar, Dutch process cocoa powder, baking soda, and salt.
  2. In a separate bowl, whisk the whole milk, melted butter, eggs, and vanilla extract until well combined. Pour the wet mixture into the dry ingredients and mix only until just combined. Do not overmix.
  3. Pour the batter into the prepared baking pan. Bake for 20 minutes.
  4. Remove the cake from the oven. Immediately spread the mini marshmallows evenly over the hot cake surface. Return to the oven and bake for an additional 5 minutes, or until the marshmallows are puffed and slightly melted, but not browned. Remove and let cool completely (about 15 minutes, accounting for remaining total time).
  5. While the cake cools, prepare the frosting. In a medium bowl, cream the softened butter until light and fluffy. Gradually beat in the natural unsweetened cocoa powder and powdered sugar. Add the whole milk and vanilla extract, beating until the frosting is smooth and reaches a spreadable consistency.
  6. Spread the chocolate frosting evenly over the marshmallow layer once the cake is cooled. Slice and serve.