01 - Preheat a non-stick skillet or griddle over medium heat.
02 - Spread unsalted butter evenly over one side of each bread slice.
03 - Arrange two bread slices, buttered side down, on a clean surface.
04 - Spread 1 tablespoon ranch dressing on the unbuttered side of each prepared base slice.
05 - Top each dressed bread slice with 2 slices cheddar cheese, 2 cooked bacon slices, and half the avocado. Season with black pepper if desired.
06 - Place the remaining bread slices on top, buttered side facing out.
07 - Cook sandwiches in the preheated skillet for 3 to 4 minutes per side, pressing gently with a spatula, until bread is golden and cheese is fully melted.
08 - Remove sandwiches from heat, allow to rest for 1 minute, then slice and serve immediately while warm.