Lightly toast 4–6 slices of bread if you prefer a firmer sandwich. If toasting, do so until just golden (1–2 minutes per side in a skillet or 2–3 minutes in a toaster). Cool briefly.

Pat lettuce dry and slice tomato into 4 even slices. Arrange the onion rings and pickle slices so they are ready for assembly.

Make spreads

In a small bowl combine mayonnaise and Dijon mustard. Stir until smooth. Spread about 1 tablespoon of the mayo-mustard mixture onto three slices of bread (these will be the interior layers). Spread softened butter thinly on the outside faces of the top and bottom bread slices if you will grill or toast the finished sandwich; otherwise leave them unbuttered.

Assemble layers

Place one slice of bread (with mayo side up) on your work surface. Layer 2 slices of ham evenly across the bread, followed by one slice of cheddar cheese. Season cheese lightly with a pinch of salt and a grind of black pepper.

Place a second slice of bread mayo-side up on top of the ham/cheese layer. Add 2 slices of roast beef, then a leaf of lettuce and 1–2 tomato slices. Season tomato with a very small pinch of salt and pepper.

Top with the third slice of bread (mayo-side up). Add 2 slices of turkey, 1 slice Swiss cheese, red onion rings (use 2 rings), and 3 pickle slices. Finish with the final slice of bread, mayo side down (buttered side out if toasting).

If making a classic club-style triple-decker, insert toothpicks through the sandwich to hold layers and, using a sharp knife, cut the sandwich diagonally into quarters.

Finish & Serve

If you buttered the outer bread faces, warm a nonstick skillet over medium heat and place sandwich cut-side down. Cook 1–2 minutes per side until golden and cheese softens slightly. Press gently with a spatula while cooking to help layers bind.

Transfer to a cutting board, remove toothpicks, and serve each quarter with optional chips or a pickle spear. Serve immediately.