2lbsrusset potatoespeeled and sliced 1/8-inch thick
2cupsheavy cream
1cupwhole milk
2tbspall-purpose flour
2clovesgarlicminced
1tspkosher salt
½tspblack pepper
¼tspnutmegoptional
1 ½cupsshredded sharp cheddar cheesedivided
½cupgrated Parmesan cheese
2tbspunsalted butter
Optional: 1/4 cup chopped chives or parsley
Optional: 1/2 tsp dried thyme
Instructions
Peel and slice potatoes thinly; soak in cold water.
Melt butter; cook garlic, whisk in flour, then add cream, milk, salt, pepper, and nutmeg. Stir in 1 cup cheddar and 1/4 cup Parmesan until melted.
Preheat oven to 375°F; grease a 9x13-inch dish. Layer half the potatoes, add half the sauce, and optional thyme. Repeat with remaining potatoes and sauce.
Top with 1/2 cup cheddar and 1/4 cup Parmesan. Bake covered for 45 minutes, then uncovered for 20-25 minutes until golden.
Rest 10 minutes; garnish with chives or parsley. Serve hot.