Melt butter in a pan and sauté onions, celery, and bell peppers until soft.
Add sautéed veggies, frozen broccoli, diced potatoes, and carrots to the crockpot.
Pour in the condensed cream of chicken soup and milk; stir well.
Sprinkle in ranch dressing mix and stir to combine.
Add cubed Velveeta cheese on top without stirring.
Cover and cook on low for 4-6 hours or high for 2-3 hours until veggies are tender.
Stir everything well, allowing the cheese to melt completely.
Serve hot, garnished with extra cheese or croutons if desired.