Replacing pasta water with canned diced tomatoes and adding a sharp pecorino Romano makes a perfect and slightly creamy tomato sauce. Add a fist full of fresh basil and you're set.
Put 2 tablespoons of the butter in a large pot over medium heat. When it is hot, add the onion and cook, stirring occasionally, until it softens, about 3 minutes. Add the pasta, raise the heat a bit and cook, stirring constantly, until it's glossy and smells toasty, about a minute. Add a little salt and pepper, then the wine and stir.2.
Let the liquid bubble away. Add the tomatoes to the pot and cook, stirring occasionally, until the tomatoes break down and the pasta absorbs most of the liquid and begins to stick to the pot, about 7 minutes. Add water, 1/2 cup at a time, stirring after each addition. When the liquid is just about absorbed, add more. The noodles should be neither soupy nor dry. Keep the heat at medium to medium-high, stir frequently and repeat as necessary; you'll need about 2 cups total.3.
Begin tasting the pasta 10 minutes after you added it; it should be tender but have some resistance when you bite. (It could take as long as 20 minutes to reach this stage.) When the pasta is ready, stir in the remaining butter and the pecorino, adding a little more water if necessary to coat the noodles in sauce. Stir in the basil and taste and adjust the seasoning. Serve right away, passing more cheese at the table.