Ragù Bolognese
2 lb. ground pork
1 lb. ground beef chuck (20% fat)
Kosher salt, freshly ground pepper
2 Tbsp. extra-virgin olive oil
2 oz. pancetta or slab bacon, chopped
1 medium onion, finely chopped
1 celery stalk, finely chopped
1 medium carrot, peeled, finely chopped
6 garlic cloves, sliced
2 Tbsp. tomato paste
¾ cup dry white wine
1 28-oz. can whole peeled tomatoes
1 cup low-sodium chicken broth
1 cup whole milk
Béchamel
7 Tbsp. unsalted butter
¼ cup plus 3 Tbsp. all-purpose flour
6 cups whole milk
4 oz. Parmesan, coarsely grated (about 1 cup)
Pinch of cayenne pepper
Pinch of ground nutmeg
Kosher salt, freshly ground pepper
Assembly
1¼ lb. dried lasagna noodles (we like De Cecco since they are wide and short)
Kosher salt
Extra-virgin olive oil (for greasing)
Ragù Bolognese
Preheat oven to 225°. Mix pork and beef with your hands in a large bowl; season generously with salt and pepper, then mix again. Form into about 18 large meatballs (they don’t need to be perfect—you’ll be mashing them later).
Heat oil in a large Dutch oven over medium-high. Working in 2 batches, cook meatballs, turning occasionally and reducing heat if bottom of pot looks in danger of scorching, until browned all over, about 6 minutes per batch. Transfer to a rimmed baking sheet as they’re done.
Reduce heat to medium. Add pancetta and cook, stirring often, until lightly browned and beginning to crisp, about 5 minutes. Add onion, celery, carrot, and garlic and cook, stirring occasionally, until softened, 6–8 minutes. Add tomato paste and cook, stirring constantly, until paste darkens, about 2 minutes. Add wine and cook, stirring occasionally, until nearly completely evaporated, 4–5 minutes. Add tomatoes, crushing with your hands, and increase heat to medium-high. Cook, stirring occasionally, until liquid is jammy and reduced by about half, 8–10 minutes. Add broth and milk and return meat to pot. Bring to a simmer. Cover pot, leaving lid slightly ajar, and transfer to oven. Bake sauce (no need to stir, but check after 1–2 hours to ensure liquid is at a low simmer, adjusting oven temperature as needed) until meatballs are falling-apart tender, 3–4 hours.
Using a potato masher, break meatballs apart and incorporate into liquid (you should have about 8 cups ragù); season with salt and pepper. Reduce over medium-low heat if needed to thicken.
Do Ahead: Sauce can be made 4 days ahead; let cool, then cover and chill, or freeze up to 3 months.
Béchamel
Melt butter in a large saucepan over medium heat. Whisk in flour and cook, whisking occasionally, until flour begins to smell a bit nutty, about 4 minutes. Quickly whisk in milk and increase heat to medium-high. Bring to a simmer and cook, whisking occasionally, until béchamel thickens, about 4 minutes. Reduce heat to medium-low and cook, whisking occasionally, until smooth and velvety, about 10 minutes. Remove from heat and whisk in Parmesan, cayenne, and nutmeg (you should have about 6 cups); season with salt and pepper. Transfer to a large bowl, cover with plastic wrap, and use within 1 hour or chill.
Do Ahead: Béchamel can be made 1 day ahead. Keep chilled. Rewarm just enough to loosen before using.