Pound the 2 chicken breasts to an even thickness (about 1/2 inch) using a meat mallet or rolling pin to ensure even cooking. Pat dry with paper towels.

Marinate chicken

In a small bowl combine 2 tbs olive oil, 1 tbs lemon juice, 1 tsp garlic powder, 1 tsp smoked paprika, 1 tsp kosher salt and 1 tsp black pepper. Rub the mixture over both sides of the chicken breasts and let rest 10–15 minutes at room temperature (or refrigerate up to 2 hours).

Cook bacon

While chicken marinates, cook 8 slices of bacon in a skillet over medium heat until crisp, turning occasionally, about 8–12 minutes. Transfer bacon to a paper towel–lined plate to drain. Keep 2 tablespoons of bacon fat in the skillet if desired for extra flavor (optional).

Cook chicken

Heat a large skillet over medium-high heat and add 1 tsp vegetable oil and 1 tbs butter. When hot, add the marinated chicken breasts and cook 4–6 minutes per side until golden and internal temperature reaches 165°F (74°C). If breasts are thick, reduce heat to medium and cover for the last few minutes. Transfer to a cutting board and let rest 5 minutes, then slice thinly against the grain.

Toast bread

Spread a thin layer of butter on one side of each of the 8 bread slices. Toast in a clean skillet over medium heat buttered-side down until golden and crisp, about 1–2 minutes per side. Alternatively, use a toaster and butter after toasting.

Prepare tomato & lettuce

Slice the large tomato into 6–8 thin slices. Rinse and pat dry 4 lettuce leaves; trim any thick stem.

Make spread

In a small bowl combine 6 tbs mayonnaise with 1 tsp Dijon mustard and 1/2 tsp lemon zest (if using). Mix until smooth. Taste and adjust seasoning with a pinch of salt and pepper.

Assemble sandwiches

Spread mayonnaise mixture on one side of 4 toasted bread slices. Layer lettuce leaf, 2 slices of tomato, a few slices of cooked chicken (divide chicken evenly between sandwiches), 2 slices of bacon, and a slice of cheddar (if using). Top with the remaining toasted bread slices, buttered side out.

Serve

Slice each sandwich in half on the diagonal and serve immediately while warm. Serve with pickles or chips if desired.

Finishing & Tips

If preparing ahead: keep cooked chicken and bacon refrigerated separately. Toast bread and assemble just before serving to prevent sogginess.

To make it lighter: substitute Greek yogurt for half the mayonnaise or use whole grain bread.