Loaded scalloped potatoes are rich, creamy, and "loaded" with flavor! This recipe combines tender potatoes baked to perfection in a velvety sauce topped with crispy bacon, green onions, and melty cheese.
Preheat the oven to 325 degrees Fahrenheit. Spray a 2-quart casserole dish with pan spray and set aside.
Peel and slice the potatoes thin, about ¼-inch thick, with either a mandoline or a sharp knife. Add the potatoes to a bowl of cold water and set aside.
In a small pan, melt the butter over medium heat and then whisk in the flour. Let this cook for 2-3 minutes before whisking in the milk and sour cream.
Reduce the heat and cook for 8-10 minutes, whisking frequently, until the sauce has thickened enough to coat the back of a spoon.
Whisk in 2 cups of the cheddar cheese and cook over low heat until the cheese is fully melted. Add most of the bacon crumbles and green onions, reserving only enough of each to sprinkle over the top. Season with salt and pepper to taste.
Drain the potatoes and dry them a bit with paper towels or a clean kitchen towel. Add the potatoes and sauce to a large, clean bowl and toss until the potatoes are evenly coated.
Transfer the potato mixture to the baking dish, arranging them as necessary to ensure they sit in even layers. Top with the remaining 1 cup of cheddar cheese and the reserved bacon.
Cover with foil and bake for 40 minutes. Uncover and bake for 25-30 minutes more until the potatoes are fork-tender and the top is starting to brown. Sprinkle with the reserved green onions before serving.