Prepare the Chicken: Place each chicken breast between two sheets of plastic wrap and pound to an even 1/4-inch thickness. Season both sides with salt and black pepper.

Assemble the Rollups: Place 2 slices of prosciutto on top of each chicken breast, followed by 2 sage leaves and a sprinkle of shredded mozzarella or fontina cheese. Roll up each chicken breast tightly and secure with toothpicks.

Coat and Sear the Rollups: Place the flour in a shallow dish and lightly coat each chicken rollup in flour, shaking off any excess. In a large skillet, heat the olive oil over medium-high heat. Add the chicken rollups and cook until browned on all sides, about 6-8 minutes.

Make the Sauce: Reduce the heat to medium. Add the dry white wine to the skillet, scraping up any browned bits from the bottom of the pan. Cook for 2 minutes until the wine has reduced slightly. Add the chicken broth and simmer for another 3-4 minutes. Stir in the unsalted butter and lemon juice until the sauce is smooth and glossy.

Finish Cooking the Rollups: Return the chicken rollups to the skillet, spooning some of the sauce over the top. Cover and cook for an additional 5-7 minutes, or until the chicken is cooked through.

Serve and Garnish: Remove the toothpicks from the chicken rollups and transfer them to a serving platter. Drizzle with the sauce and garnish with chopped fresh parsley.