Preheat oven to 375°. Cut spaghetti squash in half, lengthwise.
Coat flesh side of squash with olive oil and roast on baking pan, flesh side down, for 30 minutes, or until tender.
In a medium sauté pan over medium heat, sauté olive oil, onion and bell pepper until tender, approximately 7 to 10 minutes. Add mushrooms, spinach and white beans. Sauté for 5 minutes, until spinach has wilted. Turn off heat and add one jar of Victoria® Marinara Sauce. Toss veggies with sauce.
Remove squash from oven and scrape the flesh with a large fork to form spaghetti strands.
Toss the squash strands and veggie mixture together, then add the mixture to shelled-out squash.
Top with cheese and bake until cheese is golden-brown, 8 to 10 minutes.