1. Place potatoes and bay leaf in large saucepan, add cold water to cover by 1 inch and 1 tablespoon salt. Bring to boil over high heat, then reduce heat to medium and simmer until potatoes break apart when paring knife is inserted, about 18 minutes. Drain potatoes, discard bay leaf, and return potatoes to saucepan set on still-hot burner.

2. While potatoes are cooking, melt 1 tablespoon butter in small nonstick skillet over medium heat. Add leek and cook, stirring occasionally, until lightly browned and wilted, about 8 minutes.

3. Using potato masher, mash potatoes until a few small lumps remain. Gently add 6 tablespoons melted butter and buttermilk to small bowl and mix until combined. Add butter-buttermilk mixture, leeks, and chives to potatoes; using rubber spatula, fold gently until just incorporated. Adjust seasonings with salt and pepper; serve immediately.

NOT QUITE DONE: Potatoes that remain intact when pierced with a paring knife need more cooking.	JUST RIGHT: Potatoes that break apart when pierced with a paring knife are ready to be mashed.
OVERDONE: Potatoes that have begun to disintegrate will result in soupy mashed potatoes.