In large bowl whisk together eggs and mustards. Dip 1 chicken breast in flour to coat; pat off excess. Dip into egg mixture, then panko, coating both sides evenly. Place on parchment-lined sheet pan. Repeat with remaining chicken. Refrigerate.
To order: Heat butter or oil in non-stick pan. Sauté 1 chicken breast 8 to 10 minutes, or until golden brown, turning once. Drain on paper towels and serve at once.
Tips: Use same coating technique for chicken paillards, pork or veal scaloppine, or fish.