Roast the squash. Preheat an oven to 425°F (220°C). Place cubed squash on a rimmed baking sheet, drizzle with 2 Tbsp olive oil, then season with 1 tsp garlic powder, 1 tsp kosher salt, ½ tsp ground cinnamon, and ½ tsp freshly ground black pepper. Toss well. Cook for 20 minutes, then use a spatula to toss well. Return to the oven for an additional 15-20 minutes, or until the squash is caramelized and tender. Set aside.
Cook the pasta. Bring a large pot of generously salted water to a rapid boil. Add 12oz dried pasta, stir well, then cook according to package directions until al dente, about 11 minutes. Before draining, reserve at least 1 cup (237ml) of pasta water.
Sauté onion. Heat 2 Tbsp olive oil in a large pan over medium heat (use something with deep sides!). Add sliced onion and the thinly sliced white part of the scallions. Season lightly with kosher salt then cook, stirring occasionally, until softened, about 3-5 minutes.
Cook chorizo. Increase the temperature to medium-high, then add chorizo to the pan. Cook until it’s mostly cooked through, about 5 minutes, using a wooden spatula to help break it up as needed.
Add remaining ingredients. Stir in 3 cloves of chopped garlic and 2 Tbsp chopped fresh sage, then cook 1 minute more. Add the drained pasta directly to the pan along with the roasted butternut squash, ½ cup mascarpone cheese, 5oz fresh baby spinach, ⅓ cup of Pecorino or Parmesan, and about ½ cup of pasta water to stir. Stir well until the spinach has wilted and the pasta is evenly coated in sauce. Add more reserved water as needed. Turn the heat off, then stir in 2 Tbsp butter to finish the sauce. Taste and adjust seasoning.
Garnish, then serve! Divide the pasta into bowls, then drizzle each with a little extra virgin olive oil. Sprinkle with sliced scallion, lots of black pepper, grated cheese, and a sprinkle of flaky sea salt. Enjoy!