Preheat the oven to 200 C / 400 F / 180 FAN / Gas 6.
Peel the potatoes and onions and slice thinly. Grate the cheese.
Heat the oil over a medium heat in an ovenproof frying pan.
Cook the onions for 5 to 10 minutes until softened. Set aside.
In an ovenproof pan, melt 1 tablespoon butter over a medium heat then turn off.
Start layering the potatoes, starting with a third of the potatoes, third of the onions and a third of the cheese.
Season with salt, pepper and nutmeg and scatter over some thyme leaves.
Repeat the process twice more until all the ingredients are used.
Dot the top with the remaining butter.
Heat for 5 minutes over a medium heat to start the cooking process.
Cover the pan with foil or a lid and bake for 40-50 minutes until tender.
Remove the foil and bake for a further 10 minutes to brown.
Notes
Disclaimer:The nutritional information provided is approximate and is calculated using online tools. Information can vary depending on various factors, but we have endeavoured to be as accurate as possible.