01 -
Turn your oven on to 375°F (190°C) and grab your favorite baking dish. Give it a light coating of butter or cooking spray.
02 -
Melt your butter in a big skillet over medium heat. Toss in those sliced onions and let them cook slowly until they turn a beautiful golden brown, about 15-20 minutes. They'll smell amazing!
03 -
While your onions are doing their thing, slice those potatoes nice and thin (about as thick as a quarter). Pop them in a bowl with the cream, some salt and pepper, and those fresh thyme leaves.
04 -
Start with half your potato mixture in the baking dish, then spread half those golden onions over top. Do it all again with the rest of your potatoes and onions. Last but not least, cover everything with that beautiful Gruyère cheese.
05 -
Cover your dish with foil and let it bake for 45 minutes. Then, take off the foil and give it another 15-20 minutes until it's bubbly and golden on top. The cheese should be melted and starting to brown just a bit.