Prepare the spinach by washing and chopping it.
Sauté the spinach in a skillet until wilted.
In a large bowl, combine the wilted spinach with ricotta, mozzarella, Parmesan, breadcrumbs, garlic powder, and seasoning.
Add the beaten egg and blend the mixture until well combined.
Shape the mixture into small, even patties or balls.
Chill the shaped croquettes in the refrigerator for about 30 minutes.
Heat vegetable oil in a deep skillet over medium-high heat, enough for frying.
Fry the croquettes in batches until golden brown on all sides, approximately 3-4 minutes.
Remove croquettes and drain excess oil on paper towels.
Serve hot with your favorite dipping sauce.