Add onion, carrot, garlic, water, and chicken bullion, and cauliflower to large pot and stir to combine. Simmer until carrots are tender. Add broccoli and corn and simmer 10 minutes longer. In a small bowl whisk together milk and flour until well mixed. Add to pot and stir to combine. Add salt and pepper, to taste, and paprika. Cook over medium heat, stirring throughout, until mixture thickens and begins to boil. Reduce heat back to a simmer. Add cheese and sour cream and stir until cheese is melted. Serve with additional cheese if desired