Prepare both cake mixes separately and bake them separately according to the package directions (any size pan). 

Prepare the pudding according to package directions and chill until ready to assemble. 

Crumble the sandwich cookies in small batches in a food processor, scraping often. Set aside all but 1/4 cup. To the 1/4 cup, add a few drops of green food coloring and mix well. 

When the cakes are completely cooled to room temperature, crumble them into a large bowl. Mix with 1/2 of the remaining cookie crumbs and the chilled pudding. You may not need all of the pudding. You want the cake to be just moist, not soggy. 

Put the cake mixture into the kitty litter box. 

Put half the unwrapped tootsie rolls in a microwave-safe dish and heat until softened, about 10-15 seconds. Keep an eye on them and DO NOT MELT THEM. Shape the ends, so they are no longer blunt, and curve the tootsie rolls slightly. Bury the tootsie rolls randomly in the cake and sprinkle with half of the remaining cookie crumbs. Sprinkle a small amount of the green-colored cookie crumbs lightly over the top. 

Heat 3 or 4 of the tootsie rolls in the microwave until almost melted. Scrape them on top of the cake and sprinkle lightly with some of the green cookie crumbs. Heat the remaining tootsie rolls until pliable and shape them as before. Spread all but one randomly over top of the cake mixture. Sprinkle with any remaining cookie crumbs. Hang the remaining tootsie roll over the side of the litter box and sprinkle with a few green cookie crumbs. 

Serve with the scoop.