Move one oven rack to a low position. Preheat the oven to 400 degrees F and line and baking sheet with foil. Spray the foil liberally with non-stick cooking spray and set aside.
Set out two medium bowls. In one bowl, mix the mayo, mustard, 1/2 teaspoon salt and 1/4 teaspoon pepper. In the other bowl, mix the panko, parmesan cheese and thyme.
Place the chicken cutlets in the mayo mixture and toss to coat. Then one at a time, press each cutlet into the panko mixture on both sides to coat. Lay on the baking sheet.
Bake in the lower part of the oven for 15 minutes. (Cooking low in the oven helps the bottoms to crisp up.)
If the tops haven’t browned, move the baking sheet to a higher rack and turn on the broiler on for 1 minute. Watch to make sure they don’t burn.
Serve warm.
