Preheat your oven to 350℉.
To make the sauce:In one of your sauce pots, sauté the onion and garlic in 2 tbsp olive oil for 5 minutes – until slightly translucent. Then add the tomato paste, salt, and pepper, cook for 2 minutes more.
Last, add the crushed tomatoes, dried herbs, and butter. Let this sit while you make the pasta.
In your other sauce pot, boil water and cook pasta al dente (about 1 or 2 minutes shy of the package directions). Drain and return to the pot. Do not rinse.
To the cooked and drained pasta, add 1 cup of tomato sauce and stir to combine.
In a bowl, combine the ricotta, parmesan, and 1 cup of mozzarella.
In your 9x13 baking dish, first put a thin layer of sauce. Then add half the pasta with sauce, then dollop half the ricotta cheese mixture and pour half the remaining sauce (it's ok if the cheese and sauce don't completely cover the pasta).
Repeat - pasta, cheese, sauce. Then finish with the remaining 2 cups of shredded mozzarella cheese.
Bake covered with tinfoil for 20 minutes, uncovered for 10 more. Broil for 5 at the end if you want the browned tops.