Can I make this without heavy cream?
Yes. Half-and-half works great. Whole milk works in a pinch, but the sauce will be a little looser and more likely to break if it gets too hot. If using milk, keep the heat low and add an extra tablespoon of Parmesan at the end to help it feel richer.
How do I keep the cream from curdling in tomato sauce?
Heavy cream is the most forgiving here. If you are using milk or half-and-half, use a little extra caution: lower the heat, then temper the dairy by stirring a spoonful of warm sauce into the cream first. Once it is warmed up, pour it in slowly while stirring. After the dairy goes in, keep the sauce at a gentle simmer, not a hard boil.
What is the best penne for this?
Look for ridged penne (penne rigate). The ridges grab sauce and make the whole bowl taste more dramatic in a good way.
Can I add protein?
Absolutely. Toss in shredded rotisserie chicken, cooked Italian sausage, or sautéed shrimp. If you add sausage, brown it first, then build the sauce in the same pan for bonus flavor.
How do I fix sauce that is too thick?
Add pasta water a tablespoon at a time until it turns silky and coats the penne. If you forgot to save pasta water, warm water works, but pasta water is better.
How do I fix sauce that is too thin?
Simmer it 2 to 4 minutes longer, stirring, and add a little more Parmesan. Sauce thickens as it cools, so do not over-correct.
My Parmesan turned grainy or clumped. What happened?
Usually the pan was too hot, or the cheese was the pre-grated shelf-stable kind. Take the skillet off the heat (or keep it on very low), then add freshly grated Parmesan gradually while tossing. A splash of warm pasta water helps it melt into the sauce instead of seizing up.
