Heat oil in a large skillet, add onion and sauté until softened. Add thyme and garlic and cook for 1 minute more.
Add cream cheese and chicken broth to onion mixture and heat till cream cheese melts.
Meanwhile, in a large saucepan or dutch oven, bring a large amount of water to a boil as for pasta. Add carrots and boil for 3 minutes, add cauliflower and boil for 3 minutes more. Add broccoli and cook for an additional 3 minutes (times are approximate - adjust as necessary for your liking and size of vegetable pieces). Remove vegetables with a slotted spoon, then boil pasta following directions on the box/bag. Alternatively, you can start cooking pasta first and add vegetables in reverse order - your choice. I have done both with success. Drain pasta.
Combine vegetables, cream cheese mixture, pasta, cream, monterey jack and feta cheeses, sausage,and tomatoes (with juice) in a VERY LARGE BOWL (or conversely, 2 large bowls) and mix well.
Pour or scoop mixture into 2 or 3 casserole dishes. Can be held in the refrigerator for up to 3 days or bake at 350 degrees for 45 minutes (covered with foil for 30 minutes, then uncovered for 15 minutes). If heating from refrigerator, allow 45 minutes covered and 15 minutes uncovered.
This is easily adaptable to vegetables of your liking (or whatever is lurking in your crisper).