Put white sugar in a large baggie (or a bowl). Add half of the cinnamon rolls that have been cut into bag, close, and gently shake to coat pieces (or put in bowl and gently stir pcs. with sugar until coated).
Place one layer of cinnamon rolls into bottom of bundt pan (spray well before starting to add anything).
Sprinkle some caramel bits, then walnuts, then another layer of sugar coated cinnamon roll pieces until everything is gone and layered inside the bundt pan.
Microwave butter, brown sugar, pumpkin, and pumpkin spice for 30 sec., stir, then 30 more sec. until it's warm and bubbly.
Pour half of mixture on top of layers inside of bundt pan.
Put in preheated oven at 350 degrees for 30 -35 min. checking after 30 min. to ensure it doesn't get overdone.
Take out and loosen sides with a knife. Let it sit for at least 10 min. before turning over.
Put large plate or cutting board on top and flip over (should slide out if you sprayed it well). Reheat butter mixture and pour on top. Serve!!