Slice each chicken breast horizontally to create two thinner cutlets. For even cooking, lightly pound them to a uniform thickness of about 1/2 inch.
Grate the zest from the lemons to yield 1 1/2 to 2 tablespoons of zest, being careful to avoid the bitter white pith.
Combine the lemon zest with 1 tablespoon of olive oil in a bowl. Coat the chicken cutlets thoroughly with the lemon oil mixture.
In a shallow dish, whisk together the flour, salt, black pepper, and garlic powder.