Heat the pot: Set a large, wide pot or deep sauté pan over medium heat. Add olive oil and warm until shimmering.

Brown the meat: Add the ground beef. Season with a pinch of salt and pepper. Cook, breaking it up, until well browned with some crispy bits, about 6–8 minutes. Drain excess fat if needed, leaving about a tablespoon for flavor.

Sweat the aromatics: Add onion, carrot, and celery. Cook until softened, 5–7 minutes. Stir in garlic and cook 30 seconds until fragrant.

Build the base: Stir in tomato paste and cook 1–2 minutes to caramelize slightly. Add crushed tomatoes, oregano, bay leaf, and a pinch of red pepper flakes if using. Pour in the milk, then 3½ cups of the broth. Bring to a gentle simmer.

Season and taste: Add 1 teaspoon salt and several grinds of black pepper. Taste the liquid—it should be well seasoned since it will flavor the pasta.

Add the spaghetti: Break the spaghetti in half so it fits the pot evenly. Submerge the strands, fanning them out so they don’t clump. If needed, add the remaining 1/2 cup broth to ensure everything is mostly covered.

Simmer and stir: Reduce heat to medium-low. Cook uncovered for 12–15 minutes, stirring every 2–3 minutes to prevent sticking and ensure even cooking. Keep the simmer gentle; rapid boiling can make the pasta tough.

Adjust the texture: As the pasta cooks, it will absorb liquid and release starch, thickening the sauce. If it looks too thick before the pasta is al dente, add warm broth or water, 1/4 cup at a time. If it’s too thin when the pasta is nearly done, let it bubble a bit longer to reduce.

Finish the sauce: When the pasta is just al dente, remove the bay leaf. Stir in a small splash of milk or a knob of butter for silkiness, if you like. Taste and adjust salt and pepper.

Serve: Ladle into warm bowls. Top with a shower of freshly grated Parmesan and chopped basil or parsley. Serve immediately.