01 - Preheat the oven to 400°F.
02 - Place chicken breasts between sheets of parchment paper and gently pound with a meat mallet to an even thickness of about ½ inch. Season both sides generously with salt and black pepper.
03 - Dredge each seasoned chicken breast in all-purpose flour, shaking off any excess to ensure a light, even coating.
04 - Heat olive oil in a large oven-safe skillet over medium-high heat. Sear the chicken breasts for 2 to 3 minutes per side until lightly golden. Remove from the skillet and set aside on a plate.
05 - In the same skillet, add the finely chopped shallot and minced garlic. Sauté until fragrant, about 1 minute. Deglaze the pan with dry white wine, scraping up any browned bits from the bottom. Stir in the crushed tomatoes, chicken broth, and dried oregano. Let the sauce simmer for 5 minutes to develop flavor.
06 - Nestle the seared chicken breasts back into the simmering sauce. Lay one slice of prosciutto di Parma over each breast, then arrange the Fontina cheese slices on top of the prosciutto.
07 - Transfer the skillet to the preheated oven and bake for 10 to 12 minutes, or until the Fontina has fully melted and the chicken is cooked through to an internal temperature of 165°F.
08 - Remove from the oven and garnish with fresh basil leaves. Serve hot with extra sauce spooned over each portion.