Combine the flour, salt, garlic powder and a few grinds of black pepper in a shallow dish. Lightly dredge the chicken in the mixture, shake off the excess and set aside.
Heat the olive oil in a large pan over medium heat. Add the chicken in a single layer and cook until light golden brown and just cooked through, 2 to 3 minutes per side (don't overcook). Remove from the heat.
Separate the slices of prosciutto and lay them out on a flat surface. Center a piece of chicken crosswise over each slice. Arrange several slices of tomato on each chicken breast, then add 2 basil leaves and a portion of spinach. Wrap the ends of the prosciutto up around the chicken and toppings and press gently to seal.
Carefully transfer the chicken to a shallow baking dish coated with nonstick spray.
Top each piece of chicken with a thin slice of cheese.
Bake for 7 to 8 minutes, or until the cheese is nicely melted. Serve with a side of pasta and a green salad.
Tips for Making This Recipe
For best results, choose relatively small chicken breasts and be sure that you don't overcook them initially because the extra time in the oven could make them a little dry.
About the cheese:
Asiago is our favorite choice for this dish because its tangy flavor complements the saltiness of the prosciutto very nicely, but don't hesitate to substitute with mozzarella, provolone or fontina.