Squash and Leek Rigatoni au Gratin

Ingredients

• • 4 cups (600 g) peeled, seeded and cubed butternut squash
  • 2 tbsp (30 ml) olive oil
  • 3/4 lb (375 g) rigatoni
  • 3 cups (285 g) thinly sliced leeks (about 1 or 2)
  • 1 small onion, chopped
  • 2 cloves garlic, chopped
  • 1/4 cup (55 g) butter
  • 1/4 cup (40 g) unbleached all-purpose flour
  • 2 cups (500 ml) chicken broth
  • 1 cup (250 ml) milk
  • 8 cups (240 g) lightly packed fresh spinach, stemmed and coarsely chopped (2 bags of 6 oz / 170 g)
  • Red pepper flakes (optional)
  • Grated nutmeg (optional)
  • 1 cup (100 g) grated cheddar cheese
  • 1/2 cup (35 g) grated Parmigiano-Reggiano cheese
  • Salt and pepper