Slice each chicken breast in half horizontally. Cover a work surface with plastic wrap. Place the chicken halves on plastic wrap and cover with another sheet of plastic wrap. Use a mallet to pound each piece of chicken until it is evenly 1/4 inches (6 millimeters) thick. Season each side with salt and pepper.
Place the flour on a rimmed plate.
On another plate, combine the breadcrumbs, parmesan, salt, pepper, and zest from the lemon.
In a wide bowl, briefly beat together the eggs and juice from the lemon.
In a large wide pan, place olive oil over medium heat.
Coat a thin piece of chicken thoroughly in the flour, then dip in the beaten eggs to cover. Allow the excess egg to drip off, then coat all sides in the breadcrumb mixture. Repeat with remaining chicken.
Place the prepared chicken in a single layer in the heated skillet (in batches if needed) and cook until the bottom turns golden, about 2 minutes. Adjust heat between medium and medium low as needed to brown the chicken and cook through the center.
Flip the chicken to cook the other side and add leaves from the sage sprigs. Once golden and cooked through, remove chicken and sage to a towel lined plate.
Add the garlic to the pan and cook until just fragrant, 30 seconds to 1 minute. Pour in the wine, scraping any browned pieces on the bottom of the pan, then pour in the chicken broth. Increase the heat to medium high.
Once the liquid has reduced by half, add the butter. Adjust seasonings to taste with salt and pepper if needed.
In a small bowl, whisk together the cornstarch and water. Pour into the liquid while whisking and continue to cook until thickened.
Serve the chicken immediately topped with fried sage leaves, sauce, and lemon wedges.