1 ½ cup heavy cream at room temperature
2 garlic cloves, minced
2 tbsp unsalted butter, melted
2 ½ lbs starchy potatoes (eg. Russet, Sebago, Maris Piper, etc.)
1 tsp salt
¼ tsp pepper
2 ½ cups freshly grated gruyere cheese (or any other melty cheese, eg. colby, cheddar, havarti, etc.)
2 tsp fresh thyme leaves
Mix butter, cream, and garlic in a small bowl or jug until combined.
Peel the potatoes and slice them 1/8" thick, or use a slicer!
Spread one third of the potatoes in a 9x13 baking dish, then pour over one third of the cream mixture and scatter with one third each of the salt, pepper and thyme. Sprinkle with ¾ cups cheese.
Repeat for the 2nd and 3rd layer, but do not finish with cheese on the top of the 3rd layer.
Cover top with foil, and bake for 1 hour and 15 minutes or until the potatoes in the middle are soft (use a knife to test softness). It might take 1 ½ hours.
Once the potatoes are soft, remove foil and top with remaining cheese. Bake for a further 10 to 15 minutes until golden and bubbly. Let stand for 5 minutes before serving.
Serve.
Notes
Make sure your cream is room temperature when you mix it with the butter; otherwise it will curdle!