01 - Preheat the oven to 400°F (200°C).
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 chicken breast in 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 for 2 to 3 minutes per side until lightly golden. Remove and set aside.
05 - In the same skillet, sauté the shallot and garlic until fragrant, about 1 minute. Deglaze with white wine, scraping up any browned bits from the bottom. Add the crushed tomatoes, chicken broth, and dried oregano. Simmer for 5 minutes.
06 - Nestle the seared chicken breasts into the sauce. Top each breast with a slice of prosciutto and a portion of Fontina cheese.
07 - Transfer the skillet to the oven and bake for 10 to 12 minutes, until the cheese is melted and bubbly and the chicken is cooked through to an internal temperature of 165°F.
08 - Garnish with fresh basil leaves and serve hot, spooning extra sauce over each portion.