If serving with pasta, bring a large pot of water to a boil, then add the pasta and cook according to package directions. Drain and set aside.
Meanwhile, heat the olive oil over medium heat in a large Dutch oven or saucepan. Add the onion, sprinkle with ¼ teaspoon salt, and sauté until the onions are soft and very tender, about 5-8 minutes, stirring frequently.
Add the garlic and sauté an additional 1-2 minutes, stirring to avoid burning. Add the pumpkin puree, tomato sauce, honey (if using), 3 teaspoons salt, and water, stirring to combine. Stir on medium heat until the sauce begins to bubble (be careful, the sauce will be thick and might splatter). Turn the heat to low and simmer 10 minutes, stirring occasionally.
Add the coconut milk, cinnamon, rosemary, and sage, stirring to combine. Taste and add additional salt and pepper to taste.
If serving with pasta, toss the cooked pasta with 2-3 cups of the sauce. Serve warm with additional sauce if desired.