Thinly sliced potatoes and onions are baked in a rich cream sauce in this classic crowd-pleaser from Canada's Prince Edward Island.
4 tbsp. unsalted butter, plus more for greasing
3 cloves garlic, finely chopped
1 medium yellow onion, thinly sliced
¼ cup flour
1½ cups heavy cream
½ cup milk
3 tbsp. finely chopped thyme
Kosher salt and freshly ground black pepper, to taste
2½ lb. Yukon gold potatoes, peeled and very thinly sliced
¼ tsp. paprika
Heat oven to 350°. Grease an 8" square baking dish with butter; set aside. Melt butter in a 6-qt. saucepan over medium-high heat. Add garlic and onion; cook, stirring occasionally, until golden, 8–10 minutes. Add flour; cook, stirring, until smooth, 2 minutes. Add cream, milk, thyme, salt, and pepper; bring to a boil. Add potatoes; cook, stirring occasionally, until potatoes are just tender, 8–10 minutes. Transfer mixture to prepared baking dish. Using a spoon, press mixture down; sprinkle with paprika. Bake until golden brown and a knife inserted into middle of potatoes slides in easily, about 40 minutes.