1 hour before assembly, place cakes from freezer on counter to get to room temp.
Using an 8 inch cake circle, place a small amount of frosting and place the first layer of cake crust side down. Pipe a thick ring of buttercream around the edge of the cake. Pour half of peanut butter marshmallow creme and spread it smooth.
Place the second layer of cake, crust side down. Pipe another ring of buttercream around the edge of the cake. Pour half of chocolate ganache on cake and spread it smooth.
Place the third and final layer of cake, crust side down. Lightly spread frosting over cake and scrape 'til smooth for the crumb coat layer. Some of the cake should be showing. Freeze for 15 minutes
Place 8.5 inch acrylic disc on the top of the cake. Spread on frosting and use an icing scraper and smooth the cake. Once smooth, freeze cake with acrylic disc still on for 10 minutes.
Use a knife to cut off acrylic disc. Frost the top of the cake until smooth. Using ganache in squeeze bottle, drip the chocolate down the sides of the cake. Pour ganache on top of cake and smooth it to the edges. Freeze cake for 20 minutes to set the ganache.
Using a food processor, crumble graham crackers. Place crumbs on bottom of cake and on top around the edges in a circle. Toast the marshmallows with a torch or the broil setting on high in the oven. If broiling, place on cookie sheet and rotate every minute. Should only take 2-3 minutes. Keep watch because it could burn easy. Place marshmallows on top of ganache.