Cut the bacon in half crosswise into eight pieces. Cook in a large skillet over medium-high heat until crispy. Remove and set aside. Drain all but one tablespoon of the bacon fat from the pan and return it to the heat.

While the bacon is cooking, prep the chicken. Cut each breast in half crosswise. Using a meat mallet, a rolling pin, or other heavy object, pound each breast to a uniform thickness. Season with ground black pepper.

Cook the chicken breasts in the bacon fat until golden brown and done throughout. Add a touch of olive oil if needed during cooking.

While the chicken breasts are cooking, wrap the buns in aluminum foil and warm in a 350 degree oven for about 10 minutes. Remove and keep warm until needed.

When the breasts are done, top each with two pieces of cooked bacon and a slice of Swiss cheese. Reduce the heat to low, cover the pan, and cook until the cheese has melted.

Combine the mayonnaise and mustard in a small bowl. Spread each cut side of a bun with the mayo-mustard mixture. Top each with lettuce and one cooked chicken breast.