Make the dressing first to allow the flavors to meld. In a small bowl, combine mayo, sour cream, garlic, chives, pepper and salt. Whisk in milk to desired consistency. Cover and refrigerate until ready to use.
Make Croutons:
Oven Method:Cut bread into 3/4" cubes, crust and all. Transfer to a large mixing bowl. Sprinkle with all seasonings. Drizzle bread cubes with olive oil and butter. Toss until bread cubes have an even coating of oil, butter and seasonings.
Spread the bread in a single layer on a baking sheet and bake at 375˚F for 20 minutes or until they are golden brown and crunchy.
Stove Top Method:
Cut bread into ¾” cubes, crust and all.
Heat the oil and butter in a large skillet or frying pan over medium-high heat.
Add the bread cubes to the pan, sprinkle with seasonings.
Toast the bread cubes, tossing every minute or so, until the bread cubes are golden-brown on all sides, about 5-8 minutes total.
In a large mixing bowl, combine lettuce, tomatoes, bacon and croutons. Just before serving, drizzle with dressing and toss to combine.