Preheat oven to 400°F. Trim dark-green tops and root ends from leeks. Cut leeks in half lengthwise. Remove thick, tough outer layers (2 to 4 total, depending on size). Thoroughly wash and drain leeks, keeping them intact. Arrange in a tight single layer, cut sides up, in a broiler-safe baking dish.

In a small saucepan, boil the white wine 30 seconds. Add broth and return to a boil. Then season generously with salt and pepper. Pour the mixture over leeks and sprinkle with thyme. Cover dish with foil.

Roast for 45 minutes. Uncover and continue roasting until leeks are very soft and broth mixture is reduced by half, 20 to 22 minutes.

At this point you can sprinkle with some grated parmesan cheese or even add some butter if you like. Serve as a side or light main dish.