Creating cheesy scalloped potatoes can be straightforward if you follow these easy steps:

1. Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish.
2. Prepare the Potatoes: Peel the russet potatoes and slice them thinly, about 1/8 inch thick. Set them aside in a bowl of cold water to prevent browning.
3. Make the Cheese Sauce: In a medium saucepan, melt the butter over medium heat. Add the chopped onion and sauté until translucent, about 3-4 minutes.
4. Add Garlic: Stir in the minced garlic and cook for an additional minute until fragrant.
5. Create a Roux: Sprinkle the flour over the onion and garlic mixture. Stir well and cook for 1-2 minutes, allowing it to bubble slightly.
6. Incorporate Cream and Milk: Gradually whisk in the heavy cream and whole milk. Continue stirring until the sauce thickens, about 5-7 minutes.
7. Add Seasonings: Stir in the salt, black pepper, and paprika. Mix well, then remove the saucepan from heat. Add in 1 ½ cups of the shredded cheddar cheese, stirring until melted and smooth.
8. Layer the Dish: Drain the potato slices and layer half of them in the bottom of the prepared baking dish. Pour half of the cheese sauce over the potatoes.
9. Repeat Layers: Add the remaining potato slices on top, followed by the rest of the cheese sauce. Sprinkle the remaining ½ cup of shredded cheddar cheese on top.
10. Cover and Bake: Cover the baking dish with aluminum foil and bake for 45 minutes. Then, remove the foil and bake for an additional 15-20 minutes, or until the potatoes are tender and the cheese is bubbly and golden brown.
11. Rest Before Serving: Once done, remove from the oven and let it rest for about 10 minutes before serving. This allows the dish to set slightly for easier slicing.

These steps will guide you in creating cheesy scalloped potatoes that are both delicious and visually appealing.