Step 1

Line a baking sheet with waxed paper. Season chicken breasts with salt and pepper. Place flour on a plate. Beat eggs and Dijon mustard to blend in a shallow bowl or baking dish. Place 1 cup panko in another shallow bowl or baking dish, adding remaining 1 cup panko, or more, to dish as needed throughout process. Working with 1 chicken breast at a time, dredge in flour, shaking off excess, then dip into egg mixture, turning to coat evenly; carefully coat with panko, pressing panko gently to adhere to chicken. Transfer chicken to prepared baking sheet.

Step 2

Heat 1 Tbsp. oil and 1 Tbsp. butter in a large skillet over medium-high heat (pan should be large enough to hold 2 breasts). Add 2 chicken breasts to skillet and cook until golden brown on both sides, 8-10 minutes. Transfer chicken breasts to a paper towel-lined plate and season with salt. Add remaining 1 Tbsp. oil and 1 Tbsp. butter to skillet and repeat with remaining chicken breasts. Transfer chicken breasts to plates and garnish each with parsley and a lemon wedge.