Add oil to a large skillet, and over medium-low heat slowly cook onion, celery, carrot, garlic, cauliflower and squash. Continue cooking until onion become translucent. Add broth and bring to boil.
Use a blender to puree vegetable mixture until completely smooth. Blend in batches. Be careful with the hot vegetables and make sure to not overfill the blender. Return to skillet and simmer.
In a separate large skillet, combine soy milk and flour. Cook over medium heat for 3 to 5 minutes. Add hot vegetable puree, whisking constantly with wire whip. Bring to a simmer.
Add Parmesan and cheddar cheese. Turn off heat and stir until cheese is melted.
Cook macaroni according to directions on package. Drain and combine with sauce. Serve.