1
Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 450 degrees. Wash and dry produce.
Dice potatoes into 1⁄2-inch pieces. Trim, peel, and cut carrots on a diagonal into 1⁄2-inch-thick pieces. Halve, peel, and cut onion into 1⁄2-inch-thick wedges. Strip rosemary leaves from stems; finely chop leaves until you have 2 tsp (4 tsp for 4). Halve, core, and cut apple into 1⁄2-inch- thick wedges.