Position the oven rack to the lower third of the oven, then preheat to 450°F. While the oven is heating up prepare the radishes by cleaning, trimming and cutting them in half. You also need to wash and dry the radish leaves.
Season the radishes with rosemary, thyme, salt and pepper. In an oven-safe skillet, over medium-high, heat the oil until it begins to shimmer. Add the seasoned radishes, stirring occasionally until lightly browned, about 2 minutes.
Move the skillet to the oven and roast for 15 minutes, stirring once half way through.
Remove the skillet from the oven and place on the burner, over medium heat. Add butter to the skillet and stir until the radishes are completely coated. Toss the radish green into the skillet and cook until they are lightly wilted, about 2 minutes.
Move to a serving dish, sprinkle with grated Parmesan cheese and serve immediately.