Heat a large skillet over medium-high. Add ground beef and cook until no longer pink, stirring frequently to crumble.
Meanwhile, chop onions, slice mushrooms, and chop garlic.
Add beef and veggies to a crockpot; stir in the tomatoes, tomato sauce, and seasonings, then cover and cook on low for 8 hours.
Just before serving, cook pasta according to package directions. Drain oranges.
While pasta cooks, toss together the spinach, orange wedges, oil, and vinegar in a large bowl.
Serve sauce over pasta, garnished with freshly-grated Parmesan cheese; serve salad on the side.