Broil 5 assorted bell peppers and 8 cored plum tomatoes, turning, until charred, 15 minutes; let cool. Peel the peppers and cut into strips; peel and chop the tomatoes. Cook 3 sliced garlic cloves in 3 tablespoons olive oil in a pot over medium heat until beginning to brown, 3 minutes. Add the roasted peppers, tomatoes and any collected juices, 1 teaspoon kosher salt and a few grinds of pepper. Bring to a simmer, cover and cook, stirring occasionally, until saucy, 15 minutes. Toss with 12 ounces cooked fusilli, adding up to 1/2 cup pasta-cooking water to loosen the sauce. Off the heat, stir in 1/2 cup torn basil and season with salt and pepper. Serve with drizzled olive oil.