01 - Arrange eggs in a saucepan and cover with cold water. Bring to a boil over medium-high heat, then reduce heat and simmer for 9 minutes. Immediately transfer eggs to an ice water bath to cool, then peel and chop.
02 - While eggs are cooking, place bacon slices in a cold skillet and cook over medium heat until crisp, turning as needed. Transfer to paper towels to drain, cool briefly, then crumble.
03 - In a medium mixing bowl, combine chopped eggs, mayonnaise, Dijon mustard, halved cherry tomatoes, crumbled bacon, and fresh chives if using. Season generously with salt and black pepper.
04 - Lay out lettuce leaves and divide the egg salad mixture among them, spooning into the center of each leaf.
05 - Fold or roll the lettuce leaves around the filling and serve immediately.