Krämiga Potatisgratäng med Karamelliserade Lök

👩‍🍳 Gör så här

1. 1
   Preheat the oven to 350° F.
2. 2
   Melt together the butter and onions in a large skillet over medium-high heat. Cook, stirring occasionally until softened, about 10 minutes. At this point, you'll want to add the wine and continue to cook another 5 minutes until the onions are deeply caramelized.
3. 3
   Add the garlic and thyme, then season with salt and pepper. Cook another 2 minutes, then remove from the heat.
4. 4
   Butter a 9x13 inch casserole dish. In a large glass measuring cup, combine the cream, milk, a pinch of cayenne, salt, and pepper. Then add the Gruyere cheese. Pour 1/3 of the milk mix into the bottom of the baking dish. Layer in 1/3 of the potatoes, and 1/2 of the onions. Add another 1/3 milk mix, then 1/3 of the potatoes, and then the remaining onions. Add the remaining potatoes, then pour over the last of the remaining milk mix. Try to get the potatoes in an even layer.
5. 5
   Cover and bake 1 hour 45 minutes to 2 hours. Remove the foil and top with cheddar cheese. Bake another 20 minutes, until the cheese is golden and melty. Serve the dish warm, topped with fresh thyme.