Preheat your oven to 400°F (200°C). Toss the butternut squash cubes with olive oil, salt, and pepper on a baking sheet. Roast for about 25 minutes, or until tender and slightly caramelized. Let cool slightly.
In a large bowl, mash the roasted butternut squash until smooth. Add ricotta cheese, egg, nutmeg, and mix well. Gradually add flour until the dough comes together; it should be soft but not sticky. Divide the dough into four portions for easier handling.
On a lightly floured surface, take one portion of the dough and roll it into a long rope about 1/2 inch thick. Cut into 1-inch pieces to form the gnocchi. Optional: use the back of a fork to shape the gnocchi for added texture. Repeat with remaining dough.
Bring a large pot of salted water to a boil. Drop in the gnocchi in batches, cooking until they float to the surface (about 2-3 minutes). Remove them with a slotted spoon and place on a plate or baking sheet.
In a large skillet over medium heat, add the Italian sausage. Cook until browned, breaking it up with a spoon. Add minced garlic and chopped sage, sautéing for an additional 2 minutes until fragrant.
Add the cooked gnocchi to the skillet with the sausage. Gently toss to combine, allowing the gnocchi to absorb the flavors. If desired, sprinkle in half of the grated Parmesan cheese and stir.
Plate the gnocchi with sausage, top with the remaining Parmesan cheese, and garnish with a few extra sage leaves for color.
Notes
Serve the gnocchi in shallow bowls, drizzling a bit of olive oil on top and finishing with freshly cracked pepper for extra flavor.