Boil or steam the potatoes until soft. Place in a mixing bowl, add the butter and seasoning and mash until smooth. Set aside.
Heat the olive oil in a frying pan over a low heat, add the onion and fry gently until soft. Increase the heat, stir in the mince and cook until separated and browned all over. Add the garlic and leave for 1–2 minutes. Transfer to a bowl and stir in the rosemary. Add the Gorgonzola cheese, cream and seasoning and combine.
Take small handfuls of the potato mash and form into balls, each about the size of a large plum. Use your thumb to create a good pocket in the centre of the ball and spoon in a heaped teaspoonful of the mince mixture. Lightly press the potato around the mixture to enclose it. Repeat until all the mixture is used up.