1. Preheat oven to 400 degrees. Shred potatoes on the large holes of a box grater. Wrap potatoes in a clean kitchen towel; squeeze out liquid. Place in a medium bowl; toss with salt and pepper.

2. Heat half the butter in a 9- or 10-inch ovenproof nonstick saute pan over medium-low heat. Spread potatoes in pan evenly; press down with a spatula to flatten cake. Cook until bottom is golden and turning crisp, about 18 minutes.

3. Remove pan from heat. Invert cake onto a plate; slide back into pan. Return to heat, and spoon remaining butter around edges of pan. Cook until other side begins to get crisp, about 10 minutes, shaking pan several times to loosen.

4. Transfer to oven until cooked through and tender in the center, about 12 minutes. Cut into wedges, and serve.