Start by carefully slicing the chicken breast lengthways to get two fillet pieces. Season the chicken breasts with salt, black pepper, garlic powder, onion powder and paprika then set aside.
To a small bowl, add and combine the milk, lemon juice and egg. Place both chicken breast pieces into the milky mixture and allow them to soak for 15 minutes.
While the chicken is soaking in the milk, prepare the flour breading. Add and combine all the breading ingredients to a shallow bowl.
Remove the chicken breasts from the milky mixture and place them into the flour breading and ensure the chicken gets fully coated in the flour. Turn the chicken a few times in the flour to coat it as much as possible. Set the bowl aside for 15 minutes.
Place a pan on a medium to high heat and add in the oil. Once the oil reaches 150oC/302oF or begins to sizzle, carefully place both chicken pieces into the pan. Cook for 10 minutes turning half way through. If you have a thermometer then ensure the chicken reaches 72oC/161oF. Remove the chicken breasts and place them on a plate lined with kitchen towel.
Add 1 teaspoon of mayo on both sides of each brioche roll and spread. Place the chicken on the bottom buns then top the chicken with lettuce. Place the top bun on the lettuce and serve.