1 bunch collard greens, stems removed and leaves washed
2 tablespoons olive oil
3 spring onions, bulbous ends and greens separated
1 stalk green garlic, sliced
salt to taste
¼ teaspoon red pepper flakes (optional)
freshly ground pepper
8 to 12 ounces pasta, any shape
½ cup cooking water from the pasta
Parmigiano Reggiano cheese