1Heat oven to 425°F. In 10-inch ovenproof skillet, drizzle 1 teaspoon of the melted butter. Layer with half of the potato slices, thinly overlapping. Brush with 1 teaspoon butter. Layer with all of the apple slices. Sprinkle with salt, pepper and 1 1/2 teaspoons of the sage. Layer with remaining potato slices. Drizzle remaining 3 teaspoons butter over top. Sprinkle with salt, pepper and remaining 1 1/2 teaspoons sage.
2Place skillet on stove over medium-high heat 5 minutes. Cover; bake 15 minutes. Uncover; bake 20 to 25 minutes longer or until potatoes are browned and crisp on outside and tender on inside.
3Using oven mitts, carefully invert skillet onto serving plate. Cut into wedges to serve.