In a small bowl combine 1 tbs olive oil, 1 tsp salt, 1 tsp black pepper, 1/2 tsp garlic powder and the zest from 1/2 lemon. Rub this mixture evenly over both sides of the chicken breasts.

Preheat a grill or grill pan over medium-high heat (about 400°F / 200°C). Lightly oil the grate or pan.

Grill the chicken breasts 4–6 minutes per side, depending on thickness, until an internal temperature of 165°F (74°C) is reached and juices run clear. Remove from grill and let rest 5 minutes before serving to retain juices.

Meanwhile, halve the soft rolls and spread a thin layer of butter on cut sides. Toast cut-side down in a skillet or on the grill for 1–2 minutes until golden and warm.

Lemon & Herb Mayo

While the chicken rests, make the Lemon & Herb mayo. In a small bowl combine 1/2 cup mayonnaise, 1 tbs fresh lemon juice, 1/2 tsp lemon zest, 1 tbs finely chopped parsley, 1 tsp finely chopped chives, 1/2 tsp grated garlic, 1/4 tsp salt and 1/4 tsp black pepper.

Whisk until smooth and taste; adjust lemon, salt or herbs to preference. Keep covered in the refrigerator until ready to assemble.

Lettuce & assembly

Wash and dry lettuce leaves. If using tomato, slice into 4 even slices.

Spread about 1 tbs Lemon & Herb mayo on the bottom half of each toasted roll.

Place one grilled chicken breast on each bottom roll. Top each breast with 2 lettuce leaves (or 1 large leaf folded) and a tomato slice if using.

Drizzle or spread 1 tbs Heinz ketchup over the lettuce or tomato on each burger (adjust ketchup to taste).

Spread a thin layer of remaining Lemon & Herb mayo on the top roll half, then close the burgers. Serve immediately.