Make roasted cherry tomatoes by tossing with a little olive oil and salt and pepper, spreading on a baking sheet lined with foil, and roasting in a 425 oven for 10 minutes.
Melt butter in soup pot and add onion and garlic. Stir for 3 minutes.
Add flour and whisk until mixed, then slowly pour in broth and then milk, whisking until blended. Bring to a slow boil and cook until slightly thickened, 5-10 minutes.
Add cheese and mustard, stirring until cheese is melted. Add salt and pepper to taste. Now either carefully pour into a blender and puree, or even better, puree right in the pot with an immersion blender.
Ladle into bowls (heating the bowls beforehand in a 200 degree oven is nice!) sprinkle with paprika and garnish with the roasted tomatoes and some croutons.