Preheat the oven to 375°F (190°C). Place chicken breasts between two pieces of plastic wrap and pound to an even thickness of about 1/2 inch using a meat mallet or rolling pin.
In a mixing bowl, combine almond flour, salt, garlic powder, onion powder, and 1/2 cup Parmesan cheese. In another bowl, beat the eggs.
Dip each chicken breast into the beaten eggs, letting excess drip off, then coat in the almond flour mixture, pressing gently to adhere.
Heat oil in a large frying pan over medium heat. Fry the coated chicken breasts 4-5 minutes per side until golden brown. Fry in batches if necessary.
Spread a thin layer of keto marinara sauce in a baking dish. Place fried chicken breasts on top, cover with remaining marinara sauce, then layer with sliced mozzarella and sprinkle 1/3 cup Parmesan cheese on top.
Bake in the preheated oven for 20-25 minutes until cheese is bubbly and golden and chicken reaches an internal temperature of 165°F (75°C).
Let the Keto Chicken Parmesan rest a few minutes before serving. Pair with low-carb sides like roasted vegetables or salad.