Sweet and savory sweet potatoes and squash make this warm salad a perfect side dish.
Heat oven to 400 degrees. In a large bowl, toss together the potatoes, squash, olive oil, balsamic vinegar, butter, rosemary, salt, and pepper.
Arrange the vegetables in a single layer in two 9-by-13-inch baking pans. Transfer pans to oven, and roast vegetables until golden and tender, 45 to 50 minutes, rotating the pans between the shelves halfway through roasting.
Remove the pans from oven, and allow vegetables to cool slightly. Toss the vegetables with the arugula. Drizzle with additional olive oil and balsamic vinegar, and serve immediately.