Preheat the oven to 400 degrees . In a large bowl, toss the squash, onion, olive oil and rosemary; season with salt and pepper. Place on a baking sheet and roast until the squash is tender, about 30 minutes.
Meanwhile, in a large pot of boiling, salted water, cook the pasta until al dente; drain and transfer to a large bowl.
In a small skillet, melt the butter over medium heat and cook, stirring occasionally, until golden, about 7 minutes. Stir in the lemon juice.
Add the roasted squash, brown butter and 1/3 cup parmesan to the pasta and toss; season with salt and pepper. Top with the pine nuts and remaining parmesan.
