Set up a station to bread the chicken. One dish with flour, 1 teaspoon salt and pepper. One dish with egg beaten. One dish with breadcrumbs, lemon zest, ½ teaspoon salt, and cheese.
Dredge the chicken breast in flour, dip in eggs and coat in the panko making sure to press the breadcrumbs into the chicken. Repeat with remaining chicken breasts.
Heat oil in a large rimmed skillet over medium-high heat (you do not want the oil too hot or it will burn the coating). The oil should register at 350°F if temped with an instant read thermometer.
Once oil is hot place chicken gently in the skillet. Cook until golden brown and a thermometer inserted into chicken reads 165°, about 4-5 minutes on each side. Drain on paper towel lined plates. The chicken should be golden brown and breading firm and crunchy. Serve with lemon sauce poured over the top.
For Lemon Sauce:
In a sauce pan, whisk mustard, cream and lemon juice over medium heat till it lightly simmers.
Turn heat to low and allow sauce to slowly reduce by half. Whisk in the butter. Remove from heat and cover to keep warm while chicken cooks.