Rice Krispie Cake

• 13 tablespoons unsalted butter
• 1/4 teaspoon salt
• 15 cups mini marshmallows
• 20 cups Rice Krispies
For the filling
• 2 tablespoons unsalted butter
• 5 1/2 cups miniature marshmallows
• 5 1/2 ounces chopped chocolate
assorted extra cereals for decorating
In a large saucepan, add butter and salt - melt over medium-low. Add marshmallows - stirring until thoroughly melted. Stir in Rice Krispies until combined. Reserve about 1/4 cup of the cereal mixture and place in a small bowl - cover and set aside.
Evenly divide the mixture between two 9" round baking pans coated with cooking spray. Press mixture down until level. Set aside and let cool until set, about 30 minutes.
Filling:
In a medium saucepan, melt butter over medium-low. Add marshmallows and cook, stirring, until just beginning to melt. Add chocolate and stir until smooth. Remove from the heat.
Remove cereal mixture from the baking pans and set onto parchment paper.
While the frosting is still warm, pour onto the center of one cereal cake and spread evenly, almost to the edges. Let stand for 10 minutes. Place second cake on top and gently press down to set into the filling. Use reserved 1/4 cup cereal mixture to patch the edges if you see any frosting visible.
Decorate cake with assorted cereals - let cake stand until firm, about 30 minutes to 1 hour. If not serving right away, cover well with plastic wrap.