Heat the oil in a large pot over medium heat. Once the oil heats, add the sage and cook until crispy. Set the sage aside on a paper-towel lined plate.
Immediately add in the butternut squash, shallots, garlic and red pepper flakes to the pot and season with salt and pepper. Cook for 5-7 minutes or until onion is translucent. Pour in the broth and raise the heat to bring the mixture to a boil. Once boiling, reduce the heat to a simmer and cook until the squash is softened, 15-20 minutes.
While the squash cooks, peel and spiralize the parsnips. Set aside.
Once the squash mixture is softened and easily pierced with a fork, transfer to a high-speed blender. Wipe down the pot and set aside. Blend the squash mixture until smooth, about 1 minute. Taste and season with salt and pepper to your preference. If the mixture is too thick, add in vegetable broth.
If not using leftover Christmas ham: Set the pot down over medium heat and once heated, add in the ham or pancetta and cook for 5 minutes or until cooked through and starting to brown on edges. Then, add in the parsnip noodles, cover and toss to cook for 5 more minutes or until al dente. Then, add in the squash sauce and toss altogether to warm sauce. Crumble the sage on top and serve immediately.
If using leftover Christmas ham: Set the pot down over medium heat and once heated, add in the ham, squash sauce and parsnip noodles, toss and cook for 5-7 minutes or until noodles al dente. Crumble the fried sage on top and serve immediately.