Preheat your oven to 220°C. Bring a large saucepan of water to the boil with 1/4 tsp salt. Peel the potatoes and slice into thin rounds approximately 1cm thick. When boiling, add the potatoes to the water and cook until just tender, 14-16 mins. TIP: The potatoes are cooked when you can easily slip a knife through, but be careful not to overcook them. Once cooked, carefully drain in a colander and set aside.

Meanwhile, halve, peel and thinly slice the red onion. Thinly slice the mushrooms. Trim the carrot then halve lengthways (no need to peel). Chop into roughly 1cm wide, 5cm long batons. Pop the carrots onto a large baking tray. Drizzle with oil, season with salt and pepper then toss to coat. Spread out in a single layer, then set aside. Peel and grate the garlic (or use a garlic press). Pop the breadcrumbs and olive oil for the crumb (see ingredients for amount) into a small bowl, then season with salt and pepper. Mix together, then set aside.

Heat a drizzle of oil in a frying pan on medium-high heat. When hot, add the chicken and season with salt and pepper. Cook until browned all over, 6-7 mins. IMPORTANT: Wash your hands after handling raw chicken and its packaging. TIP: Cook in batches if necessary - you want the chicken to brown, not stew. Once browned, transfer the chicken to a medium bowl and set aside.

Return your (now empty) pan to medium heat with a drizzle of oil. When hot, add the onion and cook until softened, 4-5 mins, stirring occasionally. Add the mushrooms and a little more oil if needed, then turn the heat up slightly. Fry until the mushrooms are browned, about 5-6 mins. Stir in the garlic and cook for 1 min more. Meanwhile, pop the carrots on the middle shelf of your oven to roast until tender, 18-25 mins. Turn halfway through.

Stir the water for the sauce (see ingredients for amount) and the chicken stock paste into the pan, then bring to the boil. Stir in the creme fraiche, bring back to the boil again, then turn down the heat. Simmer gently until reduced by a third, 3-4 mins. Once the sauce has reduced, taste and season with salt and pepper, then return the chicken to the frying pan.

Transfer the chicken filling to an appropriately sized ovenproof dish. Layer on the cooked potato slices, then sprinkle over the breadcrumbs. Season with pepper and bake on the top shelf of your oven until the top is golden brown, 10-12 mins. IMPORTANT: The chicken is cooked when no longer pink in the middle. Serve straight from the dish with the roasted carrots alongside. Enjoy!