Preheat the oven to 170C/150C Fan/Gas 3.

Remove the top and bottom of the onion, peel and finely slice it. Remove the skin from the garlic and slice.

Put the double cream, onion, garlic and plenty of salt and pepper in a saucepan and heat on medium until it comes up to the boil.

While that’s on, peel and slice the potatoes into 5mm thick slices.

Once the cream and onion mixture has come to the boil, take it off the heat and add the sliced potatoes, mixing well. Leave to cool slightly.

Carefully tip the potato mixture into an oven dish ensuring all potato slices are flat in the tray. Cut a piece of parchment paper to size and place it on top before putting it in the oven to bake for 30 minutes.

After 30 minutes, remove the parchment and return to the oven for a further 50 minutes, or until golden-brown on top.

Serve straight out of the tray.