You can create a cake from scratch or use your favorite mix. Sometimes I like to jut make it easy on myself and Pillsbury is my friend. Bake the cake to the package directions in a 11 X 15 pan, make as many blocks as you like.
You will need large marshmallows (I am a fan of Jet Puff by craft)
Frosting (I make my own butter cream but you can use a store brand)