Preheat oven to 400°F. Grease eight 4- to 5-inch miniature loaf pans; arrange pans in a shallow baking pan.
In a small food processor combine salt and rosemary; process until rosemary is finely chopped.
Use a mandoline to thinly slice potatoes, placing slices in a large bowl as you go. Add butter, oil, 1 Tbsp. salt mixture, and the pepper. Toss to coat potato slices well.
Arrange potatoes standing upright to tightly fill pans. Drizzle any butter-oil mixture remaining in the bowl over potatoes. Bake 70 to 75 minutes or until tender and golden with crisp edges. Let stand 10 minutes before serving. Serve with remaining salt mixture.
Serves 8.