Prepare the chicken by slicing the breasts into cutlets and pounding them between plastic wrap to an even 0.25-inch thickness.
Season both sides of the cutlets with kosher salt and black pepper.
Set up a three-stage breading station: one bowl with 1 cup flour, one bowl with beaten eggs, and one bowl with panko mixed with garlic and onion powder.
Dredge each cutlet in flour, shaking off the excess, dip into the egg wash, and then press firmly into the panko mixture until fully coated.
In a large skillet, heat vegetable oil over medium-high heat until shimmering.
Fry the cutlets in batches for 3 to 4 minutes per side until the coating is golden brown and the internal temperature reaches 165 degrees Fahrenheit.
Transfer the fried cutlets to a wire rack or paper-towel-lined plate to drain.
Discard the frying oil and wipe the skillet, keeping any browned bits (fond) in the pan.
Melt the butter in the skillet over medium heat and whisk in 3 tablespoons of flour to create a roux.
Cook the roux for 1 to 2 minutes until it smells nutty and turns a light golden color.
Gradually whisk in the chicken broth, scraping the bottom of the pan to incorporate the fond, and simmer until thickened.
Stir in the heavy cream and season the gravy with salt and pepper to taste.
Serve the warm gravy immediately over the crispy chicken cutlets.