A question about a recipe: Marcella Hazan's Tomato Sauce with Onion and Butter

I have always followed this recipe to the letter, and it comes out perfectly every time. So, no mucking about for me!

Ever more mystifying! What is the sauce separate from the tomato chunks? If you cook it at a steady but gentle simmer, stirring from time to time, you will obtain a moderately dense and uniform sauce. Toss the drained pasta and finished sauce together very thoroughly, adding a pat of fresh butter. Spaghetti and penne or other short tubular pasta are preferable to noodles for this sauce. Forget the pasta water trick. It's ruining the sauce. Tomatoes are something you want to drain water from, not add to. Forty-five minutes is long enough, although you should be cooking not by the clock but by how it looks. What kind of tomatoes are you using? There are only two kinds for this sauce, genuine imported whole peeled San Marzano tomatoes, or fresh, firm, ripe, hand-peeled (not scalded) Roma or plum tomatoes.

When I made this, the sauce seemed to have cooked down and thickened nicely. But then I poured it over spaghetti, and I found that really, the actual sauce itself was pretty thin, hardly clinging to my noodles (this was with adding some pasta cooking water), and separated from the tomato chunks. I hoped to thicken the overall sauce by pureeing it. It tasted good, but I would like a thicker overall sauce. Maybe I didn't cook it long enough? Or cooked it too long? I cooked it for exactly 45 minutes.

P.S. Pureed tomatoes and garlic for pizza sauce might not be authentic, but it is pretty darn tasty nonetheless.

I am tempted to answer by asking, WHY? Why do you need a smoother sauce? The texture and irregularity of carefully cooked tomatoes are essential to the substance of their taste, to the volume and weight they contribute to the pasta with which they are combined. In this case, as in many others, the reliance on blending and processing erases the precious variations that are achieved through carefully executed hand cooking. As for the onion, I find it distracting. There is always someone around the kitchen who is happy to take it and eat it over bread. About pizza: I hate a sauce of pureed tomatoes over it. A real pizzaiolo bakes it with solid, cut-up pieces of San Marzano tomatoes.

I have blended the tomatoes after cooking and it's just lovely. I have also not wanted to waste the onion and blended that in as well.