Preheat oven to 400°F (200°C).
Tear keto or low-carb bread slices into pieces and pulse in a food processor or blender for a few seconds until fine to make fresh breadcrumbs.
In a small, shallow dish, whisk one large egg until well beaten.
In another shallow dish, combine the homemade breadcrumbs with half of the Parmesan cheese and the Italian seasoning. Mix well.
Lightly season the chicken cutlets with a pinch of salt and pepper. Dip each cutlet first into the beaten egg, letting any excess drip off, then press it into the breadcrumb mixture to coat thoroughly on all sides.
Place the coated chicken onto a large baking sheet that has been lightly greased or sprayed with cooking spray. Bake for 10 minutes.
After 10 minutes, carefully top each chicken piece with about ⅓ cup of low-carb pasta sauce, a generous ¼ cup of shredded mozzarella, and sprinkle with the remaining Parmesan cheese.
Return the chicken to the oven and bake for another 5-6 minutes, or until cooked through and reaches an internal temperature of 165°F (74°C). Avoid overcooking to prevent dry chicken.
For an extra golden, bubbly cheese topping, you can briefly broil for about 1 minute. Keep a close eye on it to prevent burning!
Garnish with fresh parsley or basil, if desired, and serve immediately with extra warm pasta sauce on the side.