Ingredients:

  • 1 cup unsalted butter, softened
  • 2 cups granulated sugar
  • 1 ½ cups all-purpose flour
  • ¾ cup unsweetened cocoa powder
  • 1 teaspoon baking soda
  • ½ teaspoon salt
  • 2 large eggs
  • 1 cup buttermilk
  • 1 teaspoon vanilla extract
  • 1 cup boiling water
  • 6 cups mini marshmallows
  • 1 cup chopped pecans or walnuts, lightly toasted
  • 1 cup semisweet chocolate chips
  • ½ cup heavy cream (35% fat)
  • 1 cup powdered sugar, sifted

Instructions:

  1. Preheat oven to 350°F (175°C). Grease and lightly flour a 9x13 inch metal or glass baking pan.
  2. In a large bowl, whisk together flour, sugar, cocoa powder, baking soda, and salt.
  3. In a separate bowl, whisk the eggs, buttermilk, and vanilla. Add wet mixture to the dry ingredients and mix until just combined.
  4. Carefully pour the boiling water into the batter and mix until smooth. The batter will be thin.
  5. Pour batter into the prepared pan. Bake for 30-35 minutes, or until a toothpick inserted near the centre comes out with moist crumbs attached.
  6. Immediately upon removing from the oven, evenly sprinkle the marshmallows and toasted nuts over the hot cake surface.
  7. Return the cake to the turned-off oven (using residual heat) for 5–7 minutes until the marshmallows are puffy and slightly melted/gooey. Watch carefully to prevent burning.
  8. While the marshmallows melt, prepare the glaze: Gently heat the heavy cream in a saucepan until steaming. Remove from heat and stir in the chocolate chips until smooth. Whisk in the sifted powdered sugar until the glaze is thick and glossy.
  9. Pour the warm glaze evenly over the gooey marshmallow layer.
  10. Let the cake cool completely at room temperature for at least 1 hour, then chill for another hour to allow the layers to fully set before slicing and serving.