Boil the pasta: Bring a large pot of salted water to a boil. Add pasta and cook until just al dente.
Reserve 1/2 cup of pasta water, then drain.
Sauté aromatics: In a wide skillet, warm olive oil or butter over medium heat. Add onion and cook 3–4 minutes until soft. Stir in garlic for 30 seconds until fragrant.
Add tomatoes and season: Pour in the tomato sauce.
Stir in sugar, Italian seasoning, salt, and pepper. Simmer 5–7 minutes to mellow the acidity.
Make it creamy: Lower the heat. Stir in heavy cream and milk.
Simmer gently 2–3 minutes, stirring, until the sauce looks silky.
Cheese time: Sprinkle in Parmesan and stir until melted. If too thick, add a splash of milk or reserved pasta water to loosen.
Combine: Add the drained pasta to the skillet. Toss until every piece is coated.
If using peas, chicken, or other add-ins, fold them in now.
Taste and adjust: Add a pinch of salt if needed. For extra creaminess, stir in another tablespoon of cream or a bit more Parmesan.
Serve: Top with a little more Parmesan and fresh basil or parsley if your kids like it. Serve warm.