Stir in the pumpkin puree, broth, cream, thyme, nutmeg, and red pepper flakes. Bring to a simmer, then cook slowly for 4–6 minutes, until the sauce thickens slightly and coats the back of a spoon.
Fold the drained orzo into the sauce. If the mixture seems thick, loosen with a splash of the reserved pasta water until it reaches a creamy texture that clings to the pasta.
Stir in the Parmesan, and season with salt and fresh black pepper to taste. If using greens, fold them in and cook just until wilted. Finish with lemon juice if you like a bright counterpoint to the pumpkin.
Serve warm with an extra sprinkle of cheese on top and a drizzle of olive oil for shine. The sauce should be silky and the orzo tender, with a balanced peppery-sweet-savory flavor.
Notes
Creamy pumpkin orzo with a peppery kick, a cozy fall lunch or dinner ready in about 30 minutes.