Toss the gnocchi into the pan and coat in any remaining oil in the pan to coat the flavours from the prosciutto. Add the marinara sauce and water to the pan, bring to a steady simmer, cook for another 2 minutes or until the gnocchi is tender. Dot the mozzarella across the chicken and gnocchi, place a lid on and simmer for another 2 minutes until melted and oozing. Season to taste.