How to Make It
Rinse eggplant, squash, bell peppers, and rosemary sprigs. Scrub potatoes. Trim and discard ends of eggplant and squash. Stem and seed bell peppers. Cut eggplant, squash, and bell peppers into 1 1/2-inch chunks and potatoes into halves. Combine vegetables, rosemary, olive oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper in an 11- by 17-inch roasting pan (2 to 2 1/2 in. deep); mix well.
Bake in a 400º regular or convection oven, stirring occasionally, until potatoes are browned and tender when pierced, about 1 hour. Mound on a large platter. Add more salt and pepper to taste. Serve warm or at room temperature.