Preheat your oven to 220°C/200°C fan/gas mark 7.

Bring a large saucepan of water with 1/2 tsp salt to the boil for the potatoes. Peel and slice the potatoes into 1cm thick rounds.

Halve, peel and thinly slice the onions. Peel and grate the garlic (or use a garlic press). Grate the cheese.

Once boiling, add the potato slices to the water and simmer until just tender, 8-12 mins. Once cooked, reserve some of the potato water (see pantry for amount), carefully drain in a colander.

While the potatoes are boiling, heat a drizzle of oil in a large frying pan on medium heat. 

Once hot, add the onions and mushrooms. Season with salt and pepper and fry, stirring occasionally, until golden, 10-12 mins.

Next, add the half the garlic and sugar (see pantry for amount). Cook until caramelised, 1-2 mins more.

Once the onions and mushrooms have caramelised, add the creme fraiche, vegetable stock paste, reserved potato water and half the cheese to the pan.

Mix together, bring to the boil, then remove from the heat. Season to taste with salt and pepper.

Lay half the cooked potato slices in layers in an appropriately sized ovenproof dish and pour over half the creamy onion and mushroom sauce. Drizzle over half the onion marmalade.

Repeat with the remaining potato, creamy sauce and onion marmalade, then sprinkle over the remaining cheese to finish.

Bake on the top shelf of your oven until golden brown and bubbly, 15-20 mins. TIP: Put the dish onto a baking tray to catch any drips.

Meanwhile, give your frying pan a quick wipe clean.

When your gratin is nearly ready, heat a drizzle of oil in the (now empty) large frying pan on medium heat.

Once hot, add the cabbage and remaining garlic. Stir-fry for 2 mins.

Season with salt and pepper, add a splash of water, mix well and cover with a lid (or foil). Cook until just tender, 3-4 mins.

Once cooked, stir in the butter (see pantry for amount) until melted, 1 min. Remove from the heat.

Carefully slice your potato gratin into portions and share between your plates.

Serve with the garlicky cabbage on the side. 

Enjoy!