- Peel the potatoes, keeping them whole, and ideally all about the same size (8cm). Parboil them in a pan of boiling salted water for 15 minutes – this will ensure that the insides become really fluffy.
- Drain in a colander and leave to steam dry for two minutes – this will help the fat to stick to the potatoes. Give the colander a few light shakes to chuff up the edges of the potatoes, giving you maximum surface area for a crispy exterior as they roast.
- Place the goose fat or butter and 1 tablespoon of oil in your largest roasting tray. Tip in the potatoes, add a good pinch of sea salt and black pepper, then toss to coat, and spread out in one fairly snug, even layer but with small gaps between them.
- Cover and pop in the fridge overnight.
ON THE DAY
- Preheat the oven to 180°C/350°F/gas 4.
- Squash the garlic bulbs, then lightly crush each unpeeled clove and add to the tray - this gives you sweet, caramelised garlic and adds a gentle perfume to the potatoes.
- Roast for 1 hour, or until the potatoes are crisp and golden all over.
- Remove the tray from the oven. We’re nearly there, but we’ve got one last application of love and care, which is the game-changer. Gently half-squash each potato with a fish slice or masher so they kind of push into each other and fill the tray.
- Pick the sage leaves and – importantly – toss with a little oil (this will transmit the flavour and make them deliciously crisp). Sprinkle the sage over the potatoes and roast for a further 20 to 25 minutes, or until golden and amazing. Heaven – you could even serve these on their own in a restaurant, they’re so good.
Jamie Oliver’s Christmas Cookbook by Jamie Oliver is published by Penguin Random House © Jamie Oliver Enterprises Limited (2016 Jamie Oliver’s Christmas Cookbook).