Preheat oven to 450 degrees F. Line a large, rimmed baking sheet with parchment paper. Set aside.
Slice your bell peppers into large slabs and place on prepared sheet skin side facing up in a single layer. Roast for 25-30 minutes until the tops are blistered and the peppers are fork tender. Rotate your trays halfway through baking. Remove from the oven to a bowl and cover with foil. Let the peppers cool until they are cool enough to handle, about 15-20 minutes.
Peel the blistered skin off the peppers and discard the skins. Roughly chop. Set the peppers aside for later.
In a large soup pot or Dutch oven, melt the butter over medium-high heat. Add the onions and cook 5 minutes, stirring often. Add the celery and continue to cook for 5 minutes. Add the garlic and cook for one minute, stirring often.
Lower the heat to medium and add the flour and cook for 2-3 minutes, stirring often so as not to burn. Add the undrained tomatoes, chicken broth, roasted peppers, sugar, salt and pepper. Bring to a boil and then turn down the heat to a simmer and cook for 15 minutes, stirring occasionally. Puree the mixture with an immersion blender or in small batches in a regular blender, making sure not to overfill.
Add the pasta and continue to cook until the pasta is cooked, about 10 minutes. Add the half and half and cook until heated through. Serve with croutons on top or with a grilled cheese for dipping.