Bring a large pot of salted water to a boil. Add 12 oz of penne pasta and cook according to package instructions until al dente, about 10-12 minutes. Reserve 1/2 cup of pasta water before draining, then drain the pasta and set aside.
Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the peeled and cubed butternut squash and sauté for about 8-10 minutes, stirring occasionally, until tender and slightly browned.
Add the diced onion to the skillet with the butternut squash and sauté for 3-4 minutes until softened. Stir in the minced garlic and 1 teaspoon fresh chopped sage, cooking for another minute until fragrant.
Pour in 1 cup of vegetable broth and bring the mixture to a gentle simmer. Let it cook for 5 minutes to reduce slightly and concentrate flavors. Stir in 1 cup heavy cream and mix well.
Use an immersion blender directly in the skillet to puree the squash mixture until silky. Alternatively, transfer to a blender in batches, puree, then return to the pan.
Add the cooked penne pasta to the skillet with the creamy butternut squash sauce. Toss well to coat. If the sauce feels too thick, add a splash of reserved pasta water to loosen it.
Stir in 1/2 cup grated Parmesan cheese, then season with salt and pepper to taste. Toss until cheese melts and pasta is evenly coated.
Serve hot, garnished with fresh sage leaves for color and aroma. Enjoy immediately for best flavor and texture.
