Preheat your oven to 425 degrees Fahrenheit. Spray a 1 1/2 quart baking dish with cooking spray.
As you peel and slice your potatoes, put the potatoes in a large bowl filled with the chicken stock and heavy cream. This will prevent them from browning as you prepare the rest of your recipe.
2 1/2 pounds russet potatoes, 1 cup chicken stock, 1 cup heavy cream
Over medium heat in a large Dutch oven, melt the butter. Add in the onion and cook until translucent, about 5 to 7 minutes. Add in the garlic powder, salt, thyme, and black pepper.
1 onion, 2 tablespoons unsalted butter, 1 teaspoon garlic powder, 1 teaspoon salt, 1 teaspoon dried thyme, 1/4 teaspoon black pepper
Add the potatoes, cream, and stock to the Dutch oven and bring to a simmer. Cover and cook for 10 minutes or until the potatoes are tender and can be sliced with a small knife with little resistance.
Transfer the potato mixture to the baking dish and smooth into an even layer. Top with the cheddar cheese and bake for 10 minutes. Remove from the oven, top with the fried onions. Bake for an additional 5 minutes.
1 cup cheddar cheese, 1 cup crispy fried onions
Let stand 10 minutes. Garnish with fresh parsley and serve.