1/4 cup vegetable oil
2 pounds (about 3 large) russet potatoes, peeled and grated
1 small to medium onion, finely diced
3/4 teaspoon salt
3/4 teaspoon freshly ground black pepper or more to taste
1 cup cr?e fra?he
1/2 cup half-and-half
3 large eggs
1 to 2 tablespoons minced fresh chives
1/4 teaspoon dry mustard
1 cup grated pepper jack or sharp Cheddar cheese (about 1/4 pound)
Paprika

Preheat oven to 375 degrees F.

Warm oil in a heavy, ovenproof 8- to 9-inch skillet over medium heat. Add potatoes and onion, stir to coat with oil, sprinkle in at least 1/2 teaspoon each salt and pepper, and pat mixture down. Par-cook potatoes, scraping up and patting back down several times, until golden, somewhat sticky, crispy in spots, and reduced in volume by about half, about 15 minutes. Remove from heat. Press potato mixture down around bottom and up edge of skillet to form a crust about 1 1/2 inches high. A spoon helps in shaping it evenly.

Whisk together cr?e fra?he, half-and-half, eggs, chives, dry mustard and 1/4 teaspoon each of salt and pepper.

Sprinkle cheese into potato crust, then pour cr?e fra?he mixture over cheese. Dust with paprika. Bake 25 to 35 minutes, until puffed and lightly browned and a small thin knife inserted in center comes out clean. Let sit at least 10 minutes to firm a bit before slicing. Cut into wedges and serve.