Cook the jumbo shells as directed on the box. Rinse with cold water and set aside.
Heat a saute pan with 2 Tbsp oil over medium heat, saute onions and mushrooms until soft. Add garlic. Saute until fragrant. Add spinach. Saute until wilted. At the end, add salt and pepper. Set aside.
In a medium bowl, crumble pressed tofu to resemble the consistency of ricotta cheese. (To press the tofu, place between two towels. Put a heavy can on top and let it sit for as long as you remember. Thirty minutes to hours is good)
Mix hummus into crumbled tofu. Mix in veggies.
In a 9x13 inch pan, pour 1/3 of the jar of sauce and spread evenly.
Stuff each shell with 2 Tbsp of tofu/veggie mixture. Place each shell into the pan. Continue until all the shells and filling are used up. Pour the rest of the sauce over the shells.
Cover the dish with foil and bake at 350 degrees for 30-35 minutes or until the sauce is bubbly and the shells look steaming hot.