Take out a medium sized bowl, and combine the zucchini, eggs, onion, flour, parmesan cheese, mozzarella cheese, and salt together. Be sure to stir well enough so that the ingredients distribute easily.

Now you are going to want to heat up a small amount of oil in a skillet that is over a medium high heat. Drop the zucchini mixture you mixed together earlier by spoonfuls, or however big you want your patties to turn out to be. Cook this for a good few minutes before flipping to the other side. Make sure each side of the patties are a nice golden color! That is when you know you are ready to serve your zucchini patties.