Heat a large skillet over medium heat. Lay the 6 slices of thick-cut bacon in a single layer (trim if necessary). Cook, turning occasionally, until deep golden and crisp, about 8–12 minutes depending on thickness. Transfer bacon to a paper-towel-lined plate to drain. Reserve 1 teaspoon of bacon fat in the skillet for toasting the bread (optional).

Toast bread

Spread about 2 tablespoons softened butter evenly across one side of each of the 4 slices of bread. In the same skillet (add the reserved bacon fat if using) heat over medium-low. Place bread butter-side-down and toast until golden brown, about 2–3 minutes per side. Alternatively, toast in a toaster and butter after toasting. Remove and set aside.

Prepare fillings

Make the cream cheese spread

Place 4 oz softened cream cheese in a small bowl. Season with 1/4 teaspoon of the salt and 1/8 teaspoon of the black pepper. Whip with a fork until smooth and slightly fluffy. If you prefer a thinner spread, add 1–2 teaspoons of milk and mix to desired consistency.

Mash avocado

Halve and pit the avocado. Scoop the flesh into a bowl and add 1 teaspoon lemon juice, the remaining 3/4 teaspoon salt, and remaining 3/8 teaspoon black pepper. Lightly mash with a fork until roughly creamy but a few small chunks remain. Taste and adjust seasoning with more lemon or salt if needed.

Prepare ham

If the ham slices are large, fold or roll them into sandwich-friendly pieces so they fit on the bread without overhang. Warm them briefly in the reserved skillet for 30–45 seconds per side if you prefer warm ham; otherwise use cold slices.

Assemble sandwich

Lay the 4 toasted bread slices butter-side down on your work surface.

Spread about half of the cream cheese (approximately 2 oz total, evenly divided) over two of the bread slices. On the other two slices, spread the mashed avocado (divide evenly).

On the cream cheese–topped slices, layer the ham (4 slices per sandwich, or adjust to preference). Top the ham with 3 slices of cooked bacon each (divide the 6 slices between the two sandwiches).

Add optional greens (about 1/2 cup per sandwich) over the bacon if using. Close the sandwiches by placing the avocado-topped bread on the ham/bacon slices, cream cheese side facing the ham/bacon.

Press gently, slice each sandwich in half, and serve immediately.