Mary Berry's heavenly potato gratin

For 6 people

• 900g (2lb) even-sized waxy potatoes, such as Désirée
• 1 tsp salt
• Freshly ground black pepper
• 45g (11⁄2oz) butter, melted, plus a little extra to grease
• 150ml (5fl oz) single cream

Special equipment

• 1 litre (1 3⁄4 pint) shallow ovenproof dish, buttered

For 12 people

• 1.8kg (4lb) even-sized waxy potatoes, such as Désirée
• 1 tsp salt
• Freshly ground black pepper
• 75g (21⁄2oz) butter, melted, plus a little extra to grease300ml (10fl oz) single cream

Special equipment

• 2 litre (3 1⁄2 pint) shallow ovenproof dish, buttered

Make sure you use an ovenproof dish that’s wide and shallow, so you get more of the delicious crispy golden crust. Serve with chops, grilled meat, or fish

1. Preheat the oven to 220°C (200°C fan/400°F/Gas 7). Rub off any excess dirt from the potatoes and put them unpeeled into a pan. Cover with cold water and add the salt. Cover with a lid, bring to the boil, and cook until just tender. The timing will depend on their size, but they should be soft around the edges and slightly firm in the centre. Set aside for them to cool completely.
2. Peel the skins from the potatoes and discard. Using a coarse grater, grate the potatoes into the buttered dish, seasoning between the layers with salt and freshly ground black pepper. Do not press down – they should be light and fluffy.
3. Pour over the melted butter and cream and bake for 20–25 minutes (40 minutes for 12) or until crisp and golden brown.

In the Aga