Preheat your oven to 350°F (175°C) and grease an 8x8 inch or similar-sized baking dish with butter.
Arrange half of the sliced potatoes into the prepared baking dish, creating an even layer.
In a saucepan over medium heat, combine the half-and-half cream, flour, salt, pepper, and onion powder. Stir continuously until the mixture thickens slightly, about 3-5 minutes.
Pour half of the creamy mixture over the potatoes in the dish.
Sprinkle half of the shredded cheddar cheese over the top.
Layer the remaining potato slices over the cheese and pour the remaining creamy mixture on top.
Top with the remaining cheddar cheese.
Cover the dish with aluminum foil and bake in the preheated oven for 1 hour.
Remove the foil and bake for an additional 30 minutes, or until the potatoes are tender and the top is lightly browned.
Allow to cool for a few minutes before serving.