Add the potatoes and mash into the pan. Cook until the potato and onion mixture is dry, then add the cheese and salt and pepper to taste.

Cook until the cheese is melted and everything is coagulated.

You can continue cooking the frico over a medium low flame until a crust forms on one side. Cover with a plate, and flip over onto the plate. Add a little more oil to the pan, and, when hot, slide the frico back into the pan. Cook until the frico is brown on the second side, then slide onto a plate, cut and serve — or cut and serve directly from the pan.

Alternatively, before browning the frico, you can scoop out the mixture and divide among four or more oiled ramekins. Let cool. You can refrigerate overnight if you wish.

Heat 3 more tablespoons of olive oil in the skillet. When hot, gently turn the ramekins upside down into the oil. If your skillet is large enough, cook three or four at a time. Fry on one side until crisp and brown. Flip and cook on the other side until brown. Cook the rest of the mixture like this. You can keep the cooked frico warm on a sheet pan in a 180-degree oven.