Infuse the oil by heating olive oil over low heat, adding minced garlic, red pepper flakes, and torn basil for 5 minutes.

Brown the onion by cooking it in the infused oil for 8-10 minutes until caramelized, then remove it.

Cook the tomatoes by introducing San Marzano tomatoes and simmering for 10-15 minutes.

Add the basil oil back to the pan after the tomatoes have thickened and simmer for another 2-3 minutes.

Finish the sauce by stirring in browned butter, seasoning with salt and pepper to taste.

Combine with pasta by cooking spaghetti per package instructions and tossing it with the sauce.