Bring a large stockpot of salted water to a boil. Cook the pasta according to package directions until it is just tender. Reserve 1 cup of pasta water before draining the pasta.

Pre-heat a large sauté pan over medium heat. Add the sausage and cook, breaking it up into bite-sized chunks, until it is no longer pink. Remove the cooked sausage from the pan with a slotted spoon and set it aside. Add the onion and butternut squash to the pan and stir to coat with the fat from the sausage. Add the dried sage. Sauté for a few minutes to brown the vegetables. Add the chicken stock and deglaze the pan, scraping up any brown bits on the bottom of the pan. Bring the liquid to a simmer, cover and cook for 3 to 5 minutes, until the squash is soft.

While the pasta and squash are cooking, mix the ricotta cheese with the fresh sage, salt and freshly ground black pepper in a bowl and set it aside.

Return the cooked sausage to the pan and add the baby spinach. Add the hot pasta to the pan on top of the spinach and toss to combine until the spinach has wilted. Add ½ cup of the reserved pasta water to loosen the pasta, adding more if necessary. Season to taste with salt and fresh ground black pepper. Dollop the seasoned ricotta cheese into the pasta, nestling it into the pasta to start to warm and melt. Transfer to a serving dish and garnish with a little more fresh sage if desired. Serve immediately.