Preheat the oven to 400 degrees F. Bring a pot of salted water to a boil.
Arrange the squash on a baking sheet and spray with the cooking spray to lightly coat; season with salt, pepper and a little nutmeg. Roast to tender and brown at the edges.
Place the saffron in the chicken stock in a medium pot and add the cabbage. Bring to a low boil, then reduce the heat to a simmer. Cook the cabbage to very tender, about 20 minutes.
Melt the butter in small pan over medium heat, add the sage and fry the leaves to crisp. Remove to a towel, and then crumble the leaves. Lightly brown the butter.
Boil the pasta in salted water to al dente, reserve 1/2 cup starchy water, then drain. Toss the pasta with the starchy water, squash, cabbage and stock, browned butter, crumbled sage and cheese. Toss for 2 minutes to absorb the sauce, then place in casserole and cool. Store for a make-ahead meal.
To reheat, bake at 375 degrees F, loosely covered with foil. Then top with a little cheese, and broil to crisp up the edges.
Recipe courtesy of Rachael Ray