• 1 1/2 tablespoons olive oil , plus more for drizzling
• 1 small onion , finely chopped
• 2 carrots , peeled and finely chopped
• 1 stalk celery , finely chopped
• 4 cloves garlic , minced
• 1 can (28 ounces) diced tomatoes
• Salt and freshly ground pepper , to taste

• 1/2 pound whole wheat spaghetti or linguine
• 2 tablespoons chopped flat-leaf parsley
• 1 large pinch red pepper flakes
• 3/4 cup grated Parmesan cheese
• 2 tablespoons whole wheat breadcrumbs

To make sauce: In a large saucepan, heat oil over medium heat. Add onion, carrots, celery and garlic. Cook, stirring frequently, until vegetables begin caramelizing, about 12 minutes. Turn heat to low; cook until very soft, 10–15 minutes. Raise heat to medium; add tomatoes. Bring to a simmer and partially cover. Cook 30–40 minutes, stirring occasionally. Season with salt and pepper.

Preheat oven to 450°. Bring a large pot of water to a boil. Cook spaghetti according to package directions, subtracting several minutes off cooking time so it comes out very al dente.

Drain well; add to sauce. Add parsley and red pepper flakes; toss to combine. Transfer to a 2-quart baking dish. Spread level. Sprinkle with cheese and bread crumbs. Drizzle with olive oil. Bake until top is browning and sauce is bubbling, about 15 minutes. Serve immediately.