Potatoes boulangères – so named because French bakers would offer to bake people’s potatoes in their ovens after the bread was baked – are crisp and golden on the top, soft and creamy within. They are perfect for entertaining, as they sit happily in the oven without needing any attention.
2 lb 8 oz (1.15 kg) Desirée potatoes, peeled
1 heaped tablespoon finely chopped fresh sage, plus 8 small sage leaves
2 medium onions
10 fl oz (275 ml) hot stock made with Marigold Swiss vegetable bouillon powder
5 fl oz (150 ml) milk
1½ oz (40 g) butter
a little olive oil, for dipping
sea salt and freshly milled black pepper
Preheat the oven to gas mark 4, 350°F, 180°C.
You will also need an ovenproof dish measuring 11 x 8 in (28 x 20 cm) and 2 in (5 cm) deep, lightly buttered.
Begin by peeling and cutting the onions in half and then the halves into the thinnest slices possible; the potatoes should be sliced, but not too thinly (about 3-mm thick).
Now all you do is arrange a layer of potatoes, then onions, in the dish, followed by a scattering of chopped sage, then season.
Continue layering in this way, alternating the potatoes and onions and finishing with a layer of potatoes that slightly overlap.
Now mix the stock and milk together and pour it over the potatoes.
Now put little flecks of butter all over the top and place the dish on the highest shelf of the oven for 1 hour, by which time the top will be crisp and golden and the underneath creamy and tender.
Then leave the potatoes to get cold, ready to reheat later to serve with the duck (don’t put them in the fridge). To reheat, cook on the middle shelf at gas mark 7, 425°F, 220°C, for 25 minutes. Dip the sage leaves in a small dish of olive oil and scatter them over the top of the potatoes 10 minutes before the end of the reheating time.