Place the chicken breasts on a chopping board in front of you and carefully slice each breast in half, creating two thin cutlets.
Place the chicken in a dish or large bowl suitable for marinating.
To make the marinade, whisk together the olive oil, lemon juice, minced garlic, smoked paprika, herbs, chilli flakes/red pepper flakes, salt and black pepper.
Pour the marinade over the chicken and mix, making sure each piece of chicken is completely coated.
Cover with plastic wrap and allow to marinade for at least 30 minutes but up to 24 hours in the refrigerator.
Heat an outdoor grill or grill pan over medium high heat. You can use a large skillet on a stovetop too, if preferred.
Add the chicken and cook for 2-3 minutes per side (depending on the thickness of the chicken) until golden brown on both sides and cooked through.
Remove from the heat and allow to rest for 5 minutes.
To assemble the burgers, toast the hamburger buns then top with spicy mayonnaise, lettuce leaves, the grilled chicken and any burger toppings of your choice.