In a medium mixing bowl, mash the ripe avocado until mostly smooth. Add the mayonnaise and sour cream, then stir until creamy. Stir in chives, dill, parsley, garlic, onion powder, mustard, and lemon juice. Season with salt and pepper, and refrigerate for at least 30 minutes.
Flatten chicken breasts to 1/2-inch thickness, season with salt and pepper. Heat olive oil in a skillet over medium-high heat and cook chicken for 4–6 minutes per side until golden and cooked through. Let rest before slicing.
Preheat oven to 400°F (200°C). Arrange beef bacon on a baking sheet and bake for 15–20 minutes until crispy.
Prepare vegetables: wash and dry lettuce, slice tomatoes, and if using, soak onion in ice water for 10 minutes to mellow its flavor.
Toast bread slices until golden brown. Optionally brush with butter before toasting.
Assemble the sandwich: spread avocado ranch on the first slice of bread, then layer with lettuce, tomatoes, half of sliced chicken, beef bacon, and cheese. Top with a second slice of bread spread with ranch. Repeat layers with remaining ingredients and top with the last slice of bread. Secure with toothpicks and slice in half.
Serve immediately with your choice of sides like chips or salad.
Notes
Notes
For extra flavor, add smoked paprika to the chicken. Keep the sandwich assembled just before serving to avoid sogginess.