Melt 8 tablespoons butter in a large Dutch oven or saucepan over medium heat. Add 1 minced shallot and 8 minced garlic cloves and cook until softened, 4 to 5 minutes. Don't let them brown, if they start to, turn the heat down.
Stir in 4 pounds roughly chopped fresh tomatoes, 2 thyme sprigs, 2 teaspoons kosher salt, and 1/2 teaspoon black pepper and cook, uncovered, over medium or medium-high heat. You want a pretty nice boil, but you don't want to splatter your entire kitchen with tomatoes, so keep the heat in that sweet spot. Stir often and keep cooking until the majority of the liquid has evaporated, 45 minutes to an hour. It will look VERY liquidy for a long time, don’t worry, it will thicken as you continue to cook it!
When the sauce is almost ready, cook 1 pound spaghetti in very salty water until al dente - aka, almost tender but not quite. Use tongs to transfer the spaghetti directly to the spaghetti sauce so that about 1/4 cup or so of pasta water gets incorporated into the sauce. Turn off the heat for a few minutes, then stir in 1/2 cup grated Parmesan. If you don't take the pasta off the heat first, the Parmesan will clump up instead of melting into the sauce. Taste and season with more salt and pepper as needed.
Divide between 4 to 6 bowls and garnish with more Parmesan and black pepper. If you love basil, throw some basil on there, but sometimes I like a tomato pasta to just be all about the tomato!