Step 1

Preheat oven to 400°F with 1 rack in middle position and 1 rack positioned 6 inches from heat source. Pour marinara sauce into an 11- x 7-inch broiler-safe baking dish, and set aside.

Step 2

Season chicken with salt, Italian seasoning, and pepper. Heat oil in a large skillet over medium-high until shimmering. Cook chicken, smooth sides down, undisturbed, until browned, 4 to 5 minutes. Flip chicken, and cook until chicken is browned, 3 to 4 minutes. Remove from heat.

Step 3

Arrange chicken breasts evenly over marinara sauce in prepared dish, and top each with a slice of mozzarella. Transfer baking dish to middle rack in preheated oven, and bake until sauce is bubbling and a thermometer inserted in thickest portion of chicken registers 160°F, about 20 minutes. (Temperature will rise after broiling.)

Step 4

Meanwhile, stir together panko, Parmesan, butter, and thyme in a small bowl. Set aside.

Step 5

Remove from chicken oven, and top each chicken breast with panko mixture. Place baking dish on rack 6 inches from heat source. Increase oven temperature to broil, and broil until panko mixture and cheese start to lightly brown, 2 to 3 minutes. Remove from oven, and garnish with parsley.