- 2 tablespoons unsalted butter
- 1 small onion, minced
- 2 medium garlic cloves, minced (about 2 teaspoons)
- 3 cups heavy cream
- 1 cup whole milk
- 4 sprigs fresh thyme
- 2 bay leaves
- 2 teaspoons table salt
- 1/2 teaspoon ground black pepper
- 4 lbs russet potatoes, peeled and cut into 1/8″ thick slices
- 1 cup shredded cheddar cheese (about 4 ounces)
- Heat oven to 350F.
- Melt butter in large Dutch oven over medium-high heat until foaming subsides.
- Add onion and sauté until soft and it begins to brown, about 4 minutes.
- Add garlic and sauté imto; fragrant, about 30 seconds.
- Add cream, milk, thyme, bay leaves, salt, pepper, and potatoes. Bring to a simmer.
- Cover, adjusting heat to maintain light simmer. Cook until potatoes are tender.
- Remove and discard thyme and bay leaves.
- Transfer mixture to a 3 quart gratin dish and sprinkle with cheese.
- Bake until cream has thickened and is bubbling around sides and the top is golden brown (about 20 minutes). Let cool for 5 minutes before serving.