Ingredients:
- 16 cloves garlic, thinly sliced
- 1/3 cup extra-virgin olive oil
- 2 medium onions, halved and sliced
- 1/8 teaspoon red pepper flakes, or more to taste
- Kosher salt
- 12 cups torn winter greens, such as kale, chard, escarole or mustard greens (about 2 1/2 pounds)
- 12 ounces spaghetti
- 1/4 cup grated pecorino romano cheese
