Dice the onion and mince the garlic. Sauté both in a skillet with the olive oil over medium heat, until the onion is soft and transparent (about 3-5 minutes). Meanwhile, slice the zucchini into half-moons.

Add the chipotle powder to the onion and sauté for about one minute more. Finally, add the pumpkin purée, chicken broth, salt, and pepper to the skillet and stir until the ingredients are combined and smooth.

Turn the heat down to medium-low and allow the sauce to simmer for 15 minutes. When 6 minutes have elapsed, add the zucchini. When the sauce starts its 15 minute timer, also cook the pasta according to the package directions, then drain in a colander.

Once the sauce has simmered for 15 minutes, turn the heat down to low and stir in the milk. Add the cooked and drained pasta to the skillet, stir to combine with the sauce, and let it heat in the sauce over low for 2-3 minutes.
Finally, stir in the grated Parmesan, top with a little cracked pepper, and serve.