Trim fat and gristle off chicken breasts.
Cut chicken breasts in half then butterfly the thick part of the breast (if it's thick enough). This will create up to 3 pieces of chicken per breast.
Pound to 1/4 inch thick.
Season chicken on both sides with salt and pepper.
In a shallow dish mix a heaping 1/4 c all-purpose flour, 1 1/4 tsp salt and 1 tsp pepper.
In another shallow dish mix 2 eggs with 2 tablespoons of water.
In a third shallow dish mix panko breadcrumbs and parmesan cheese.
Dredge chicken first in the seasoned flour on both sides followed by the eggs, making sure to shake off excess and finally the panko mixture.
Place coated chicken on a sheet pan and allow to sit in the fridge for at least an hour. This ensures the coating won't slide off during or after cooking.
Preheat a thin layer of olive oil in a pan just under medium heat.
Cook chicken breasts in batches for 3 minutes per side, adding oil as needed. Wipe out excess breadcrumb coating left behind, so it doesn't burn onto the next batch of chicken.
Place cooked chicken on a sheet pan lined with paper towels in a 200-degree oven to stay warm while the rest of the chicken cooks.
In a separate pan preheat olive oil just under medium heat while you mince your garlic.
Cook garlic 2 minutes in the oil before adding heavy whipping cream.
Thicken the heavy whipping cream for 10 minutes before adding lemon juice, Dijon mustard, chicken stock, butter, salt and pepper.
Cook sauce for 5 minutes.
Ladle sauce over chicken and serve with mashed potatoes.