In a large bowl, mix together mashed potatoes, mozzarella, egg, flour, jalapeno, garlic and ham till combined. The mixture should be thick and should hold its shape. If its too loose, add a tablespoon of a flour at a time (this will depend on the consistency of your mashed potatoes)
Use an ice cream scoop to scoop out the mixture and form it into patties which are about 1/3 inches in thickness. Coat each cake evenly in a thin coating of breadcrumbs and set aside.
Heat oil in a pan and fry the patties in a single layer on each side for 3-4 minutes till golden brown on both sides.