Caramelized onion & roasted garlic pasta.

bulb garlic

olive oil

butter

sliced onions (about 1 to 2 onions)

chicken or vegetable broth, divided (plus more as needed to thin)

homemade or storebought tagliatelle (or pasta of your choice)

Greek yogurt (the creamier and less tart, the better -- I liked Fage best for this)

freshly ground black pepper,

Parmesan cheese, for topping (optional)