Halve potatoes; toss with 2 tablespoons olive oil. Place in a 15x10x1-inch baking pan. Brush corn with 1 tablespoon olive oil; add to pan. Lightly sprinkle potatoes and corn with salt and ground chipotle pepper or chili powder. Roast in a 425 degrees F oven for 25 to 30 minutes or until potatoes are tender. Cool just until corn can be handled; cut corn off cob. Place potatoes, cut side down, on a serving plate; top with corn and sprinkle with prosciutto. Makes 4 servings.