First Step: Prep and Bake Potatoes. Begin by preheating your oven to 425ºF (220ºC). Thoroughly scrub the russet potatoes and pierce each with a fork. Wrap every potato individually in foil to retain moisture. Place them directly on the oven rack and bake for about 1 hour, until the potatoes are tender through to the center. Once baked, allow them to cool to room temperature, then refrigerate wrapped overnight or for at least 8 hours. This chilling step enhances shredding quality and texture.

Second Step: Prepare the Shallots and Garlic. In a medium pan over medium heat, melt 1 tablespoon of unsalted butter. Add the finely chopped shallots and sauté gently for 3-5 minutes until they become soft and translucent, which mellows their sharpness. Next, add the minced garlic and cook for another 1-2 minutes until fragrant but not browned. Remove from heat and transfer the mixture into a large mixing bowl.

Third Step: Shred the Potatoes. Unwrap the chilled potatoes and grate them whole directly into the bowl with the shallots and garlic, including the skins for extra texture and flavor. If large pieces of skin remain, tear them into smaller bits to help distribute the texture evenly throughout the mix.

Fourth Step: Mix in Cheese and Sour Cream. Grate the sharp white cheddar cheese if you haven’t done so already. Add about 1 1/2 cups of the cheese into the potato mixture, reserving the rest for the topping. Pour in 1 1/2 cups of sour cream along with 2 teaspoons of kosher salt and 1/4 to 1/2 teaspoon of freshly ground black pepper. Gently mix everything together using your hands or a large spoon, being careful not to compress the mixture too much, so the bake stays fluffy and creamy.

Fifth Step: Assemble the Bake. Lightly grease a 7×11 or 8×11 inch baking dish. Spread the creamy potato mixture evenly into the dish without pressing down hard, maintaining the airiness of the dish. Sprinkle the reserved grated cheddar evenly on top to create a melty, golden crust once baked.

Final Step: Bake and Serve. Place the dish in the oven preheated to 425ºF (220ºC) and bake for about 30 minutes until the casserole is heated through, the cheese topping is bubbly, melted, and golden brown. For an extra deep golden crust, broil the bake for 2-3 minutes more, keeping a close eye to avoid burning. Once out of the oven, let the Romanoff casserole rest for 15 minutes to set before serving.