This is a beautiful cryptic-crossword clue. Slow and low is the key. You want fat, creamy curds, rather than rubbery globules of overcooked protein. The only way to guarantee this is to cook over the lowest possible heat. Use a heat diffuser if you have one. If not, go to the lowest flame and remove the pan from the heat if it gets too hot. There’s no need for milk or cream; just good, fresh eggs, butter, salt and pepper.