Here's a wonderful side dish from Chef Brandon Miller that showcases baby leeks to their best advantage.
If baby leeks aren't available, choose the smallest leeks you can find. Homemade basil oil is easy to make, especially if you have abundance of fresh basil leaves - but if time is short, you can use a commercial brand, or substitute walnut or hazelnut oil instead.
Position a rack in the middle of the oven and preheat to 325 degrees F. Butter an 8-inch square baking dish and a piece of parchment paper cut to size (for the top); set aside.
Cut off the stem ends (roots) and green tops of the leeks. Slice the leeks lengthwise, leaving one inch near the root end intact to keep the leeks from falling apart. Wash thoroughly under cold water to remove all sand.
Place the leeks in the prepared baking dish and cover with the stock. Salt and pepper lightly, then cover with the parchment paper, buttered side down. Cook until leeks are tender and the stock is reduced to a glaze. Turn the leeks 2 or 3 times while baking. Cool to lukewarm.
While the leeks are cooling, mix the vinegar with a pinch of salt and pepper. Whisk in the oil and cream. Correct the seasoning and add the chives. Pour the vinaigrette mixture over the leeks and serve lukewarm.
Basil Oil: If you're making your own, be sure to plan in advance so the oil is ready in time for you to assemble the leek dish.
In a large saucepan, bring 4 quarts of water to a boil with the salt. Add the basil and cook for 15 seconds. Drain through a sieve and immediately plunge the basil into an ice water bath to stop the cooking process. When cool, drain again and squeeze all the water from the basil with your hands.
Place the basil and the oil in a blender and pulse a few times to break up the herbs. Then blend for 2 minutes to purée.
Strain the infused oil through cheesecloth or paper coffee filters. Transfer to a sterilized glass bottle or jar and cover. Refrigerate for up to 2 weeks.