Heat your cooking oil to 170 °C (338 °F). While it heats, cut 2 large chicken breasts in half horizontally and sprinkle with 2 pinches salt and pepper on both sides.
Wrap the chicken in plastic wrap and use a meat tenderizer or rolling pin to pound it until it's 1cm thick. (about 1/2 inch)
In a bowl, mix 100 ml water, 2 medium egg(s) and 100 g all-purpose flour to make a thick batter.
Add 50 g panko breadcrumbs and 4 tbsp grated parmesan cheese to a plate, and mix them together.
Pour 6 tbsp cake flour onto a plate and coat the surface of the chicken. Brush off any excess to ensure the coat is even.
Once the oil is ready, dip your chicken into the batter.
Cover the chicken in the panko mixture, making sure it's fully covered, before placing it straight in the oil.
Fry for 6 minutes (or until golden) turning the katsu over halfway through to make sure it's evenly cooked.
Transfer to a wire rack and allow any excess oil to drip off.