Preheat the oven to 400 degrees F. Put the potatoes, garlic, carrots and rosemary on a large sheet tray or pan. Drizzle with olive oil and season with salt and pepper. Roast until browned and crisp, 45 minutes to1 hour, tossing halfway through.
Toss with the radicchio and serve.
Recipe courtesy of Gabriele Corcos and Debi Mazar