Place a large skillet over medium heat. Add the 4 slices of thick-cut bacon in a single layer. Cook 3–5 minutes per side, flipping occasionally, until crispy but still slightly pliable. Transfer bacon to a paper-towel-lined plate to drain. Reserve 1 tsp bacon fat in the skillet and discard excess (or wipe skillet and use fresh oil for steak if preferred).

Season Steak

Pat the 6 oz steak dry with paper towels. Season both sides with 1/2 tsp kosher salt, 1/4 tsp freshly ground black pepper, and 1/4 tsp garlic powder. Let the steak rest at room temperature for 5 minutes while you heat the pan.

Cook Steak

Heat the same skillet over medium-high heat and add 1 tsp vegetable oil (or the reserved bacon fat). When shimmering, add the steak and sear 2–3 minutes per side for medium-rare (time will vary with thickness). Cook to desired doneness (internal temperature ~130°F/54°C for medium-rare). Transfer steak to a cutting board and let rest 4–5 minutes, then slice thinly against the grain into pieces sized for sandwich stacking.

Egg

While the steak rests, crack 1 large egg into a small bowl and whisk with 1 tsp milk and 1/8 tsp salt until blended. Heat a small nonstick skillet over medium-low and add 1 tsp butter. When butter foams, pour the egg in and cook gently to make a sunny-side-up or over-easy egg: cook undisturbed 2–3 minutes until whites are set but yolk still runny; if you prefer over-easy, flip carefully and cook 10–20 seconds more. Remove to a plate and keep warm.

Bread & Spread

Spread 1 tbs mayonnaise on one slice of bread and 1 tbs softened butter on the outside of the other slice (butter side will be griddled). On the mayo side, add 1 tsp Dijon mustard and, if using, 1 tsp hot sauce plus 1/2 tsp honey; spread evenly.

Heat a clean skillet or griddle to medium. Place the buttered-outside slice butter-side down on the skillet and toast 1–2 minutes until golden. Remove briefly.

Sandwich - Assembly

On the mayo/mustard-spread slice (not toasted side), layer the cheeses: 2 slices sharp cheddar, then 1 slice provolone or Swiss. Add the warm sliced steak in an even layer on top of the cheese so residual heat softens it slightly. Add the 4 slices of cooked bacon on top of the steak.

Place the cooked egg on top of the bacon, yolk side up. Add tomato slices (3) and one leaf of lettuce, then the pickle halves pressed lengthwise as desired.

Top with the toasted bread slice butter-side up and press lightly. Return the assembled sandwich to the skillet (butter side down) and cook 1–1.5 minutes on medium-low with a lid or large bowl over it to melt cheeses and warm through. Flip once if needed and cook an additional 30–45 seconds. Remove to a cutting board.

Rest the sandwich 1 minute, then slice in half with a sharp knife. Serve immediately.