Broccoli-Cheddar Hash-Brown Casserole

medium russet potatoes (about 2 1/2 pounds total)

Kosher salt and freshly ground pepper

shredded sharp cheddar (8 ounces)

Dijon mustard

Greek yogurt, plus more for serving

sliced scallions (from about 4), plus more for serving

broccoli florets, cut into bite-size pieces

large eggs, lightly beaten

bacon (about 8 slices)

unsalted butter