Preheat the oven to 425°F and line a baking sheet with parchment paper.
Peel the butternut squash, remove seeds and cut into ½" cubes. Place butternut onto the baking sheet with 1 teaspoon of dried thyme, ½ of garlic powder, ¼ salt, and a drizzle of olive oil. Combine together and bake in the oven for 30-40 minutes.
Remove butternut squash from the oven and set aside.
Start to cook the pasta as per package instructions in salted water until al dente. Make sure to reserve 4 cups of pasta water before straining.
In the meantime, sautee the onions with a ½ tablespoon of olive oil and ¼ teaspoon of salt until softened. Remove from heat and add to a medium heat-safe bowl.
Add extra oil to the pan and add the sliced King oyster mushrooms to the pan with a pinch of salt. Cook until softened.
There are 2 options for making this dish - Option 1: Half of the butternut squash will be blended in the sauce and the other half will remain whole and tossed into the pasta. The 2nd Option: Blend all the butternut squash into the sauce.