Preheat oven to 400 degrees F. Line a rimmed baking sheet with parchment paper. Toss cubed butternut squash with 1 1/2 tablespoons olive oil, 1/4 teaspoon sea salt, and 1/8 teaspoon pepper. Spread in a single layer with no overlapping pieces.

Roast the squash for 15 minutes. Flip the pieces, then continue roasting for 10 to 15 more minutes until the edges are lightly caramelized and the squash is fork-tender. Total roast time is 25 to 30 minutes. Set aside.

While the squash finishes roasting, bring a large pot of salted water to a boil. Cook the orecchiette according to package directions for al dente. Before draining, reserve 1/2 cup of the starchy pasta water. Drain the pasta and do not rinse it.

Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add the sausage and break it into crumbles. Cook until fully browned with no pink remaining, about 6 to 8 minutes.

Reduce heat to medium. Add the butter and shallot to the skillet. Cook, stirring, for 2 minutes until softened. Add the chopped sage and cook for 1 minute.

Add the minced garlic and chopped spinach. Stir and cook for about 1 minute until the spinach wilts. Stir constantly to prevent the garlic from burning.

Add the drained pasta and 2 tablespoons of the reserved pasta water. Toss to coat. Add more pasta water one tablespoon at a time if the pasta looks dry.

Gently fold in the roasted butternut squash. Taste and season with salt and pepper. Serve immediately with grated Parmesan and red pepper flakes.