1️⃣ Preheat the oven to 425ºF (220ºC). 🔥

2️⃣ Pierce each potato using a fork. Then, wrap the potatoes in aluminum foil and place them on a baking dish. Bake in the preheated oven for 40-60 minutes or until ready. Check the readiness using a fork; if potatoes are fork tender, remove them from the oven and let cool completely. 🥔🔪

3️⃣ Refrigerate the cooled potatoes overnight or for at least 3-4 hours. ❄️

4️⃣ When ready to make potatoes in the casserole, preheat the oven to 350ºF (175ºC). 🔥

5️⃣ Remove potatoes from the refrigerator, grate, and place in a large bowl. 🥔🧊

6️⃣ Add minced shallots, 2 cups grated white cheddar cheese, sour cream, garlic powder, salt, and freshly ground white pepper. Mix until completely combined. 🧅🧀🥄

7️⃣ Grease a 9×13 inch casserole dish with non-stick cooking spray. Then, transfer the potato mixture to the dish. 🥄🧈

8️⃣ Top with the remaining 1 cup grated white cheddar cheese and grated parmesan cheese. 🧀

9️⃣ Bake in the preheated oven for 25-35 minutes or until golden brown. Enjoy! 🍽️✨