Adapted from Marcella Hazan's Tomato Sauce With Onion & Butter.
For this off-roading version, I wanted to stay true to the original recipe's ease and hands-off nature. But I also aimed to bump up the flavor a bit with basil, oven-roasted garlic, and a little bit of heat.
Turn on oven to 400 degrees. Cut the very top off of the head and place cut side up on a square of aluminum foil. Drizzle with olive oil and a pinch of salt. Seal the packed at place in the oven
In a medium saucepan, combine tomatoes, onion, butter, salt, red pepper flakes, and basil. Cook on medium-low, or until the sauce reaches a constant low simmer. Check occasionally and cook for 45 minutes
After 30 minutes of simmering, bring pot of salted water to boil. Cook pasta to al dente according to directions.
When 45 minutes have passed, remove the garlic from the oven and the foil packet. Add tomato sauce to food processor or high speed blender. Carefully (its very hot!) squeeze the roasted garlic from the skins into the blender. Pulse or puree to desired consistency. It can be totally smooth or chunky - up to you! If you prefer, you can also skip this step and just break up the tomatoes with a spoon, and discard the onion halves if you like.
Add some or all of the sauce to cooked pasta, depending on how saucy you like it. Garnish with basil, burrata, and/or grated parmesan.