Start by pounding each chicken breast to an even 1/2-inch thickness—this ensures they cook uniformly and stay juicy. While you're doing this prep work, whisk together the olive oil, lemon juice, honey, Dijon mustard, smoked paprika, garlic powder, salt, and pepper in a bowl or measuring cup. This marinade will be your flavor foundation, so take a moment to taste it and adjust seasoning if needed. I like to use fresh lemon juice whenever possible—it makes a noticeable difference in brightness compared to bottled.

Place the pounded chicken breasts in a shallow dish or resealable bag and pour the marinade over them, making sure each piece is well coated. If you have time, marinate at room temperature for 30 minutes, which is perfect for a weeknight dinner. For deeper flavor development, refrigerate for up to 6 hours. Either way, you'll develop a beautiful flavor profile that infuses the chicken.

While the chicken marinates, prepare all your sandwich components: slice the tomatoes into 1/4-inch thick slices, thinly slice the red onions, and tear or separate the lettuce into individual leaves. Arrange these on a cutting board or plate so they're ready to assemble. About 10 minutes before your marinating time is done, preheat your grill to 375°F. Having everything prepped and your grill ready means you won't have any downtime between cooking and assembly—I find this keeps the chicken hot and the sandwiches coming together smoothly.

Remove the chicken from the marinade (let excess drip off) and place on the preheated grill. Cook for 4-6 minutes on the first side without moving them—this creates nice grill marks and locks in flavor. Flip the chicken and cook for another 4-6 minutes. In the last minute of cooking, if using cheese, lay a slice of cheddar on top of each breast and close the lid to allow it to melt. The chicken is done when it reaches an internal temperature of 155-160°F at the thickest part.

Transfer the grilled chicken to a clean plate and let it rest for 5 minutes. This resting period allows the juices to redistribute throughout the meat, keeping each bite tender and moist. While the chicken rests, place your hamburger buns on the grill or in a toaster to lightly toast them—this adds texture and prevents them from getting soggy from the toppings and creamy base.

Spread a thin layer of nonfat Greek yogurt on the bottom bun of each sandwich, which provides a creamy base layer. Layer the lettuce, then tomato slices, then red onion slices on top, seasoning the tomatoes lightly with salt and pepper. Place one warm grilled chicken breast (with melted cheese, if using) on top, then close the sandwich with the top bun. Serve immediately while the chicken is still warm.