Red sauce from “the bear”

Seems this may be an amalgam of sauce recipes from Scarpetta’s and Marcella Hazan.
Very simple recipe, but very good.
For the basil oil:
1/2 cup olive oil, bunch of basil (stems and leaves), 6 large cloves crushed garlic, 1/2tsp crushed red pepper flakes, ample salt. Steep all these ingredients in the oil. May strain the flavored oil, but this recipe calls to blend it all up once it’s cooled.
For the sauce:
28 oz can San Marzanno tomatoes
1 yellow onion, halved
1/2 stick unsalted butter plus 2 tbsp olive oil
Melt butter with oil. Place onion cut side down to brown while the butter browns. Once onion and butter are browned, crush tomatoes by hand into pan. Add all sauce from tomato can to pan. Mix well to incorporate, breaking down the tomatoes. Season with salt to taste(I added quite a bit). Bring up to boil, then simmer 30mins. Remove onion halves and add in basil oil. Mix well and simmer until sauce thickens to your liking.
Add 1 lb Al dente spaghetti and mix well. May add pasta water if needed.
Serve with fresh chopped basil and Parmesan.
This was super easy to make and tastes great.