Step 1

Position oven rack in top position; preheat broiler.

Step 2

Combine flour, salt and pepper in a shallow dish. Place chicken between 2 large pieces of plastic wrap. Pound with the smooth side of a meat mallet or a heavy saucepan until the chicken is an even 1/4-inch thickness. Dip the chicken in the flour mixture and turn to coat.

Step 3

Heat 2 teaspoons oil in a large nonstick skillet over medium-high heat. Add spinach and cook, stirring often, until wilted, 2 to 3 minutes. Transfer to a small bowl.

Step 4

Add 1 teaspoon oil to the pan. Add half the chicken and cook until golden, 1 to 2 minutes per side. Transfer to a large baking sheet. Repeat with the remaining 1 teaspoon oil and chicken; transfer to the baking sheet.

Step 5

Top each piece of chicken with the wilted spinach, marinara sauce and Parmesan. Sprinkle with mozzarella. Broil until the cheese is melted and the chicken is cooked through, about 3 minutes. Serve on rolls.