Preheat oven to 400°F.
Slice cold chicken breasts in half horizontally to create cutlets. Pound the chicken to an even ½-inch thickness. Season with salt and pepper and set aside to come to room temperature while preparing the other ingredients.
Combine the mozzarella and fontina cheeses; set aside. Place the eggs in a shallow bowl or pie plate and whisk until blended. Pour the all-purpose flour in a second shallow bowl and set aside. In a third shallow bowl combine the panko bread crumbs, garlic powder, oregano, crushed red pepper, salt, pepper and cornstarch. Once blended stir in the grated Parmesan cheese.
NOTE: If serving with spaghetti start heating a pot of water.
Pat the chicken pieces dry with paper towels then dip in the flour to coat completely. Next dip both sides of the floured chicken in the egg allowing any excess to drip back into the bowl. Finally coat the entire cutlet in the panko mixture pressing gently so the crumbs adhere. Transfer to a baking sheet and repeat with remaining cutlets.
NOTE: Start cooking the spaghetti and warm the marinara. Set aside and keep warm.
Pour enough vegetable oil in a large, nonstick skillet (cast iron works well) to reach of depth of 1/4-inch. Heat over medium-high until shimmering.
Using tongs, carefully place 2 breaded cutlets in the skillet and cook without moving until the bottom is crispy and deep golden brown, about 3 minutes. Turn the chicken over and cook until golden. Remove to a paper towel lined plate to drain and repeat with the remaining cutlets.
Place the cooked and drained chicken on the now empty baking sheet. Spread a heaping spoonful of marinara sauce on top. Top each with the mozzarella fontina mixture. Bake for 8 to 10 minutes or until cheese is melted. For golden browned cheese, heat under the broiler for 2 to 4 minutes more.
Serve the Chicken Parmesan over hot spaghetti noodles tossed in the remaining marinara. Garnish with fresh basil leaves and parsley if desired.