Boil the potatoes in a large pot of salted water until tender. Drain and mash the potatoes in a bowl. Stir in the butter and allow this to melt all the way through. Sprinkle in the flour and combine well. Season.
If using chorizo, fry the chorizo until a little crispy and blitz (or chop) into a very fine crumb. Add the chorizo and grated cheddar cheese to the mashed potatoes and mix well.
Shape the mixture into small croquettes.
Dip each croquette into flour, then into the beaten egg, then coat with breadcrumbs.
Heat oil in a frying pan over medium heat. Fry the croquettes until golden brown on all sides.
Serve the chorizo and cheddar potato croquettes hot with a dollop of Irish Builin Blasta smoked onion mayonnaise, a small strip of Serrano ham and finely diced chive.