• 2 tablespoons extra-virgin olive oil, plus more for baking dish
• 1 medium onion, finely chopped
• 1 (28-ounce) can whole San Marzano tomatoes in juice, passed through a food mill with juice
• 1 bay leaf
• Salt
• Freshly ground black pepper
• 1 pound ziti pasta
• 2 large eggs
• 1/4 cup whole milk
• 1/2 pound Pecorino Toscano cheese, cut into 1 ⁄4-inch cubes
• 1/2 pound 1/4-inch-thick prosciutto slices, cut into 1 ⁄4-inch cubes
• 3/4 cup freshly grated Parmigiano-Reggiano cheese

Heat oil in a large skillet over medium-high heat. Add onion, reduce heat to medium-low, and cook, stirring occasionally, until softened, about 7 minutes. Add puréed tomato, bay leaf and pinch salt and pepper; bring to a simmer. Reduce heat to low and cook, covered, for 1 hour and 15 minutes. Remove and discard bay leaf.

Heat oven to 400°.

Bring a large pot of salted water to boil. Add ziti and cook for 7 minutes (the pasta will not be tender); drain and transfer to a large bowl. Add sauce and stir to combine. In a small bowl, lightly beat together eggs and milk; add to pasta and stir to combine. Stir in Pecorino and prosciutto.

Lightly oil a 3- to 4-quart baking dish; transfer pasta to dish and sprinkle with Parmigiano-Reggiano. Bake until top is lightly golden and pasta is al dente, about 15 minutes. Serve immediately.