1.1 Preheat oven to 180°C/350°F. Grease three 1-litre (4-cup) ovenproof dishes.
2.Melt butter in a large heavy-based saucepan over medium heat; cook onion and garlic, stirring, for 5 minutes, or until onion is soft but not browned. Add half the mushrooms; cook, stirring occasionally, for 5 minutes. Add remaining mushrooms; cook, stirring occasionally, for 8 minutes or until mushrooms have released their juices and most of the liquid has evaporated. Stir in wine; bring to the boil. Reduce heat; simmer until liquid is reduced by half. Remove from heat; season to taste.
3.Combine cheeses and chopped rosemary in a small bowl. Cover base of the dishes with slightly-overlapping potato slices. Sprinkle with one-third of the cheese mixture, then half the mushroom mixture. Repeat with another layer of potato and remaining mushroom mixture. Arrange remaining potato slices, slightly overlapping, around the edge of the dishes. Stir milk and cream together; pour over potato layers. Refrigerate remaining cheese mixture.
4.Cover dishes loosely with foil. Bake for 1 hour or until bubbling. Remove foil; sprinkle remaining cheese mixture over potato. Bake for 30 minutes or until potato is tender and top is golden. Stand for 15 minutes before serving. Serve topped with extra rosemary.
We used a combination of king brown, swiss brown and button mushrooms; you can use any combination of mushrooms you prefer. Use a mandoline or V-slicer to cut the potatoes into very thin slices.
If you’re entertaining vegetarians or vegans this Christmas, our recipe, which is also gluten-free, is a tasty option as a centrepiece main course. Brimming with punchy Mediterranean flavours, it’s bound to be a real showstopper.