Preheat the oven to 400 degrees F. Put 2 to 3 tablespoons of oil in a glass baking dish. Place the tomato rounds in the dish and flip them to coat both sides with the oil. Bake until softened, about 20 minutes, flipping them after 10 minutes. Remove the tomatoes from the oven and cool. When cool, slice off the skins. Dice the tomatoes and set aside.
Heat the remaining teaspoon of oil in a 3-quart saucepan over medium heat. Add the onion, bell pepper and garlic and cook, stirring occasionally, until the onions are translucent, 5 to 6 minutes. Add the broth, water, almond milk, tomato paste, salt and pepper, whisking until the tomato paste is incorporated. Simmer, partially covered, 15 minutes. Add the tomatoes, basil and rosemary and simmer until the flavors are blended but the soup is still chunky, 5 to 8 minutes. Serve with the herbed croutons.
The soup will keep for up to 5 days in a covered container in the refrigerator.