Pasta with Yogurt, Spinach, and Sweet Onions | Umami

Ingredients

• 3 tablespoons olive oil, plus more for drizzling
• 4-5 large yellow onions sliced
• kosher salt and freshly ground black pepper
• 1 pound fettuccini
• 12 ounces plain sheep’s milk yogurt (such as Old Chatham Creamery brand, make sure it’s plain) or 1 1/2 cups thick, strained full-fat Greek-style plain yogurt
• 6 ounces fresh spinach (optional)
• 1 cup grated pecorino or Parm