Celeriac, potato and anchovy gratin

I love the idea of cooking everything in one dish (quick, easy, no washing up!) so Sue Quinn's book Roasting Tray Magic is right up my street.

I picked out this recipe which is like a cross between a gratin dauphinoise and the Swedish dish Jansson's Temptation with celeriac replacing half the potato. It's not vegetarian given the anchovies but you could obviously leave those out.

There is also you will notice a fair amount of cream! I think I'd be inclined to reduce the double cream to 300ml - the size of a mid-sized carton - which should be enough for the amount of celeriac and potato involved. (In fact I used slightly more of both I made it last night and it was fine) Sue is also right in saying a mandolin makes the task of cutting them a LOT easier!

Oh and the cheesy, crispy topping is absolutely irresistible!

Celeriac, potato and anchovy gratin

Serves: 4 | Takes: about 1 hour, plus 5 minutes cooling

Knobbly old celeriac is a sadly undervalued root vegetable. It might not be photogenic, but it’s absolutely delicious, with a sweet, nutty flavour reminiscent of the celery family of which it is a member. The anchovies add a gorgeous depth of flavour – no fishiness at all.

400ml milk, plus extra if needed

400ml double cream (see note above)

2 garlic cloves, crushed

3 anchovy fillets, very finely chopped

2–3 thyme sprigs

freshly ground black pepper

300g celeriac

300g waxy potatoes

100g grated Comté cheese

green salad, to serve (optional)

For the topping:

100g sourdough or country-style bread, torn into small pieces

2 tbsp olive oil

30g grated Parmesan cheese

Preheat the oven to 190°C/375°F. Combine the milk, cream, garlic, anchovies and thyme in a 30 x 20 x 5-cm roasting tray and season with pepper.

Peel and very finely slice the celeriac and potatoes, ideally on a mandolin, adding the vegetables to the creamy tray liquid as you go to prevent them browning. Bake for 20 minutes, shaking the tray halfway through. Add a little more milk if necessary so the vegetables are just submerged. Meanwhile, mix all the topping ingredients together in a bowl. Set aside.

When the vegetables have had their 20 minutes, sprinkle over the Comté, then the topping mix. Bake for a further 30 minutes – the vegetables should be beautifully tender when the time is up. Leave to cool in the tray for 5 minutes before serving – a green salad is the perfect accompaniment.

What to drink: We drank a bottle of Chablis which is what we happened to have open but other white burgundy and, in particular, Jura chardonnay would work well too.

From Roasting Tray Magic by Sue Quinn (Quadrille, £14.99) Photography © Faith Mason