2 tablespoons unsalted butter
1 medium onion minced
2 gloves garlic minced
1 tablespoon chopped fresh thyme
1 1/4 teaspoons table salt
1/4 teaspoon ground black pepper
2 1/2lbs russet potatoes peeled and sliced into about 1/8″ thick rounds
1 cup low-sodium chicken broth
1 cup heavy cream
2 bay leaves
1 cup grated sharp cheddar cheese
1/2 cup Parmesan cheese
Preheat oven to 425F
Melt butter in a large Dutch oven over medium-high heat until the foaming subsides. Add onion and cook while stirring occasionally until lightly browned and soft (about 4 minutes). Add garlic, thyme, salt, and pepper. Cook for about another 30 seconds. Add potatoes, chicken broth, cream, and bay leaves. Bring to a simmer. Cover, reduce heat to medium-low, and simmer for about 10 minutes. discard bay leaves.
Transfer the mixture to an 8″x8″ baking dish and press into an even layer. Sprinkle the top evenly with cheese. Bake in oven about 16 minutes until the cream is bubbling around the edges and the top is golden brown.
Let cool 10 minutes before serving.