Marinate the chicken breasts in olive oil, garlic powder, paprika, salt, and pepper for at least 30 minutes.
Preheat your grill to medium-high heat.
Remove the chicken from the marinade and grill for about 6-7 minutes on each side, or until cooked through.
Toast the bread slices on the grill until golden brown.
Mix mayonnaise and mustard in a small bowl to create a sauce.
Once the chicken is done, let it rest for a few minutes before slicing.
Spread the sauce on one side of each toasted bread slice.
Layer the sliced chicken on one slice of bread.
Add pickles and lettuce on top of the chicken.
Top with the second slice of bread, cut in half, and serve immediately.