Place the cod in cold water to cover for 2 to 3 days. Keep refrigerated and change the water at least 4 times a day to rehydrate and rinse out most of the salt.
Drain the cod and place in a large pot and cover with 2 inches of water. Cook until flakey, about 30 minutes. Drain and cool the cod completely.
Melt the butter in a large pan set over medium heat. Add the garlic and onions, and saute until soft. Add the flour and stir for 2 to 3 minutes. Pour in the hot milk, a little at a time, stirring constantly. Add the pepper, then add the parsley and cod, and mix until combined. Remove from the heat and cool to room temperature.
Using your hands, form 2 tablespoons of the mixture into a small cylinder. Repeat for the remaining mixture to make about 20 croquettes.
Beat the eggs and place in a shallow bowl. Place the breadcrumbs on a separate plate. One at a time, dip the croquettes in the beaten eggs and then roll in the breadcrumbs.
In a deep-sided frying pan set over medium-high heat, add enough oil to fill the pan 2 to 3 inches high. Fry the croquettes in batches until golden brown, 3 to 4 minutes. Place on paper towels to drain excess grease, and then serve hot.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of Forno's of Spain, Newark, NJ