Mozzarella-Spinach Chicken in Rich Tomato Sauce

Preheat the oven to 375°F.

In a saucepan over medium heat, melt 1 tablespoon of butter. Add the frozen chopped spinach and cook until all the liquid has evaporated, about 10 minutes. Season it with 1/4 teaspoon each of the salt and black pepper.

Place the flour in a shallow dish. Pound the chicken breasts until they are about 3/4 inches thick using a meat mallet. Season the chicken breasts with 1/2 teaspoon of salt and 1/4 teaspoon of black pepper, then coat them lightly in the flour.

In a large oven-safe skillet over medium heat, melt the remaining 4 tablespoons of butter. Add the flour-coated chicken breasts and brown on each side, about 3-4 minutes per side. Remove the chicken from the skillet and set aside.

Reduce the heat to low and add the tomato marinara sauce to the skillet. Stir to incorporate any browned bits from the bottom of the pan into the sauce. Nestle the browned chicken back into the skillet.

Top each chicken breast with the cooked spinach, then place a slice of mozzarella over the spinach. Transfer the skillet to the preheated oven and bake for 15-20 minutes, until the chicken is fully cooked and the mozzarella is bubbly and browned.