In a large frying pan, heat the olive oil over medium heat, Add the squash, onion, garlic and red pepper flakes to the pan and season with salt and pepper. Cook for 8 to 10 minutes, stirring occasionally, until the onion is translucent.
2 lb butternut squash, peeled, seeded, and cut into small 1/2 inch chunks (about 3 cups), 2 tbsp olive oil, 1 medium yellow onion, chopped, 2 garlic cloves, chopped, pinch of red pepper flakes, 1/2 teaspoon salt, 1/4 teaspoon black pepper
Add the vegetable broth to the frying pan and bring the mixture to a boil. Next, reduce the heat and simmer, uncovered, until the squash is soft and the liquid is reduced by half; this should take approximately 15 to 20 minutes. You might need to add more broth, if your pan gets too dry.
2 cups vegetable broth
While your sauce is simmering, cook your pasta according to the package directions. Reserve one cup of the pasta water before draining your noodles.
12 ounces rigatoni
Remove the pan from the heat and allow it to cool slightly. Transfer the contents of the pan to a blender and puree the mixture until it is smooth; you may have to do this in batches. Be mindful that blending hot ingredients can cause steam to escape from the top of your blender - be careful not to burn yourself. Season with salt and pepper.
Using the same frying pan that you used to prepare your sauce, combine the cooked pasta, the squash puree, ¼ cup of the pasta water, the heavy cream, and the parmesan cheese. Cook over medium heat making sure that the sauce coats the pasta evenly. Add more of the reserved pasta water as needed. Cook until heated through, approximately 2 minutes. Season with more salt and pepper if desired.
1/4 cup heavy cream, 1/2 cup parmesan cheese
Serve the pasta topped topped with the fried sage. Add more grated parmesan at this point if desired.