Photograph: Martin Poole
Cook the potatoes in boiling salted water with the garlic cloves for 20-25 minutes until tender; drain well.
Mash the potatoes and garlic with the olive oil. Gently reheat, stirring, then stir in 3 tablespoons of the grated parmesan.
Spoon the mash into a serving dish and sprinkle over the remaining cheese.