1 Tablespoon extra virgin olive oil
  1 small onion, chopped
  salt & pepper
  2 garlic cloves, minced
  6 cups baby spinach
  4 chicken breasts, pounded very thin
  2 vine-ripened tomatoes, sliced
  4oz mozzarella cheese, sliced
  1/2 cup fresh basil leaves

Directions

1. Preheat oven to 400 degrees then line a sheet with with foil, spray with nonstick spray and then set aside.
2. Heat oil in a large skillet over medium heat then add onion, season with salt and pepper, and then saute until translucent, 3-4 minutes. Add garlic then saute for 30 more seconds. Add spinach then cook just until wilted, 2-3 minutes. Set aside to cool slightly.
3. Brush and season both sides of the pounded chicken breasts with extra virgin olive oil, salt, and pepper. Mound 1/4 of the spinach mixture on one end of the chicken breasts, then layer on sliced tomatoes, mozzarella cheese, and fresh basil. Drizzle with extra virgin olive oil then sprinkle with a bit more salt and pepper. Fold other end of chicken over and secure with a toothpick. Place onto prepared baking sheet then bake for 15 minutes, or until cooked all the way through.