Preparation Slice each leek in half lengthwise without cutting all the way through the other side; rinse under cold water (gently opening layers) until water runs clear. Pat dry. Heat oil in a large skillet with a lid over medium-high heat. Add shallot and bacon and cook, stirring, until bacon is crisp, about 3 minutes. Add garlic and leeks, season with salt and pepper, and cook, occasionally turning leeks and stirring gently, until leeks are bright green, about 5 minutes. Add wine to skillet; bring to a boil, reduce heat, and simmer until slightly reduced, about 2 minutes. Add broth; bring to a boil, reduce heat, and simmer, partially covered, until leeks are just tender, 8–10 minutes longer. Mix in butter. Serve leeks topped with chives. DO AHEAD: Leeks can be rinsed 1 day ahead. Wrap in a damp paper towel and chill.
Preparation Slice each leek in half lengthwise without cutting all the way through the other side; rinse under cold water (gently opening layers) until water runs clear. Pat dry. Heat oil in a large skillet with a lid over medium-high heat. Add shallot and bacon and cook, stirring, until bacon is crisp, about 3 minutes. Add garlic and leeks, season with salt and pepper, and cook, occasionally turning leeks and stirring gently, until leeks are bright green, about 5 minutes. Add wine to skillet; bring to a boil, reduce heat, and simmer until slightly reduced, about 2 minutes. Add broth; bring to a boil, reduce heat, and simmer, partially covered, until leeks are just tender, 8–10 minutes longer. Mix in butter. Serve leeks topped with chives. DO AHEAD: Leeks can be rinsed 1 day ahead. Wrap in a damp paper towel and chill.