Bring a large pot of salted water to a boil, and add the chopped butternut squash. Cook for about 8 minutes.
In the meantime, add 2 tablespoons of extra-virgin olive oil to a pan. Once the oil is hot, add about 8 sage leaves. Let them crisp for about 30 seconds on each side and then remove them from the heat and place them on the side for the final topping.
In the same pot, add the chopped onion and 4-6 sage leaves, add a quarter cup of water and let the onion soften.
Once the butternut squash is cooked, remove it from the water using a slotted spoon or mesh skimmer. Add the squash straight into the pan with the onions.
In the same boiling water you used for the butternut squash, cook the pasta until al dente according to the package directions, stirring from time to time. Reserve 1 cup of the pasta cooking water before draining.
Place the cooked butternut squash, onions, and sage into the blender or food processor. Add the oat milk a bit at a time, and season with salt and pepper. Blend until smooth.
Drain the pasta, then add back to the pan, add the butternut squash sauce, and if necessary, add a bit of the boiling water you saved to thin the sauce.
Serve the pasta on individual plates, with freshly grated pepper, crumbled fried sage leaves, and your favorite topping (here, I used a combination of shaved walnuts and nutritional yeast - but you can use parmesan or pecorino if you are not vegan).