Plus: More Vegetable Recipes and Tips
Preheat the oven to 400°. In a large bowl, toss the squash with the onions, olive oil and brown sugar; season with salt and pepper. Spread the squash on a baking sheet. Roast for 1 hour, or until the squash and onions are tender and browned on the edges. Transfer the vegetables to a serving bowl.
Set a small skillet over moderately high heat. When it is hot, add the butter and cook until bubbling, about 3 minutes. Add the sage leaves and cook for about 2 minutes, until the butter is browned and the leaves are crisp. Season the browned butter and sage with salt, pour over the squash and serve warm.