To Make The Cake
Preheat your oven to 350ºF and grease a 13×9-inch pan with cooking spray.
In a medium bowl whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt. Add in eggs, milk, oil, and vanilla extract and using an electric mixer, beat for 2 minutes. Slowly stir in boiling water then pour into prepared pan and cook until a clean toothpick inserted comes out clean, about 40 minutes. Top with marshmallows and place back in oven for one minute more. Remove from oven and cool.
To Make The Frosting
In a large bowl cream the butter with an electric mixer until light and fluffy. Add milk, powdered sugar, cocoa powder, and vanilla and beat until incorporated. Stir in chopped nuts.
Top cake with frosting and serve.
The nuts are optional in this cake but we love the crunch they give.
You can always make these into 24 cupcakes, cooking about 25 minutes.
Serve this cake with a bit of Chicory Coffee.