Makes:4 to 6 servings
Make-ahead casseroles are perfect for feeding a bunch of guests at a tailgate, potluck brunch, or holiday breakfast. This hearty combo of sautéed bell pepper and onion mixed with shredded potatoes, bacon, cheese, and sour cream is easy to put together, bake, and reheat in the oven the next day—you can even warm it on the grill. Serve it with scrambled eggs and a pitcher of Bloody Marys.
Heat the oven to 350°F and arrange a rack in the middle. Coat a 9-by-9-inch metal baking pan with butter (if you’re not planning to reheat the casserole on a grill, a ceramic or glass baking dish is OK to use); set aside.
Place the bacon in an even layer on a rimmed baking sheet and bake until crisp and browned, about 15 to 20 minutes. Remove to a large paper-towel-lined plate and set aside to cool.
Meanwhile, melt the measured butter in a large, wide pot or Dutch oven over medium heat. Add the bell pepper and onion, season with salt and pepper, and cook, stirring occasionally, until softened, about 5 minutes. Add the flour and cook, stirring occasionally, until the flour is no longer raw-tasting, about 1 minute.
While whisking constantly, slowly pour in the milk and whisk until smooth. Let the mixture come to a boil and remove from the heat. Whisk in the measured salt, sour cream, and 1 cup of the cheese and season with pepper; set aside.
Grate the potatoes on the large holes of a box grater (you should have about 5 cups of shredded potatoes), add to the pot, and stir to combine.
Chop the cooled bacon into small dice, add it to the potato mixture, and stir to combine.
Transfer the mixture to the prepared baking dish, spread it into an even layer, and sprinkle with the remaining 1 1/2 cups of cheese. Bake until browned all over, bubbling around the edges, and the potatoes are cooked through, about 1 hour (cover the dish with aluminum foil if it’s browning too quickly).
To make ahead and reheat in an oven or on a grill, let the cooked casserole cool to room temperature. Cover with aluminum foil and refrigerate for up to 2 days. When ready to reheat, let the covered casserole sit at room temperature for 1 to 1 1/2 hours, then place in a 350°F oven or on a medium grill (about 350°F to 450°F) until heated through, about 20 to 30 minutes.