Prepare pudding mix and chill until ready to assemble.
5.1 ounces vanilla instant pudding mix
Crumble the sandwich cookies in small batches in a food processor, scraping often. Set aside all but about 1/4 cup.
25 ounces vanilla sandwich cookies
To the 1/4 cup of cookie crumbs, add a few drops of green food coloring and mix using your fingers until it reaches an even green color.
When cakes are cooled to room temperature, crumble them into the new litter box. Toss with half the remaining cookie crumbs and the chilled pudding. Mix in just enough of the pudding to moisten it. You don’t want it soggy. Combine gently.
Put three unwrapped Tootsie Rolls in a microwave safe dish and heat until soft and pliable. Shape ends so they are no longer blunt, curving slightly. Repeat with 3 more Tootsie Rolls and bury them in the mixture. Sprinkle the other half of cookie crumbs over the top.
Scatter the green cookie crumbs lightly over the top. (This is supposed to look like the chlorophyll in kitty litter.)
Heat 3 Tootsie Rolls in the microwave until almost melted. Scrape them on top of the cake; then sprinkle with cookie crumbs.
Spread the remaining Tootsie Rolls over the top; take one and heat until pliable, hang it over the side of the kitty litter box, sprinkling it lightly with cookie crumbs. Serve with a new pooper scooper.
Pick two flavors of cake mix. Either yellow and chocolate, or white and chocolate. Having the two stark color differences helps give the cake a more realistic look. Be sure to grab the ingredients needed on the back of the boxes to prepare the cake mixes as well.
Cake mix weights have changed over the years. It won't make a drastic difference if your cake mix weighs in at 15.25 ounces or 13.25 ounces. Either will work.
You can grab a small, cheap kitty litter box to serve it in, same goes for the pooper scooper. I found mine at the dollar store, and it was the smallest one they offered. It goes without saying that the box should be brand new! Give it a good wash before using. You don't want too large of a cat box as the cake won't take up that much space. Try to find one that's rather shallow if possible. The photos here show this cake made in an 18x14x5 box.