01 - Preheat oven to 400°F. Position the rack in the center.
02 - Place chicken breasts between sheets of parchment paper and gently pound to an even thickness of about ½ inch. Season both sides generously with salt and black pepper.
03 - Dredge each seasoned chicken breast in flour, shaking off any excess to create a light, even coating.
04 - Heat olive oil in a large oven-safe skillet over medium-high heat. Sear the chicken for 2 to 3 minutes per side until lightly golden. Remove 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 white wine, scraping up any browned bits from the bottom.
06 - Add the crushed tomatoes, chicken broth, and dried oregano to the skillet. Stir to combine and let the sauce simmer for 5 minutes until slightly thickened.
07 - Nestle the seared chicken breasts into the simmering sauce. Lay one slice of prosciutto over each breast, then arrange Fontina cheese slices on top.
08 - Transfer the skillet to the preheated oven and bake for 10 to 12 minutes, until the Fontina is melted and bubbly and the chicken is cooked through to an internal temperature of 165°F.
09 - Remove from the oven, garnish with fresh basil leaves, and serve hot with extra sauce spooned over each portion.