I saw these being made at a charity wine auction in a palazzo near Frantoia, outside Florence. I suppose it was an Italian equivalent to a church fete, but conducted with great aplomb.
Preheat the oven to 180°C/Gas 4 and line a baking tray with a silicone baking sheet or greaseproof paper. In a large bowl, cream the butter and sugars, then beat in the eggs. Add the flour, spoonful by spoonful. When all mixed in, add the vanilla and chocolate chips or pieces. Spoon th