Preheat oven to 400F.
In a large bowl mix the squash, onion, olive oil and chopped rosemary; season with salt & pepper. Add to baking dish and roast until the squash is tender, stirring occasionally.
Bring a pot of salted water to a boil. Add your pasta and cook until al dente, reserving one cup of pasta water. Drain and transfer to your serving dish.
While pasta is cooking, melt butter in a saucepan over medium heat and cook, stirring until golden (approx. 6 minutes) Stir in lemon juice.
In the serving bowl with pasta, add the roasted squash, brown butter and parmesan, mix well. Pour in about 1/4 cup of the reserved pasta water to loosen everything up a bit. Add salt and pepper to taste. Top with another sprinkle of parmesan and the toasted pine nuts.