Preheat oven to 400°F. Mix sage, salt and pepper in small bowl. Layer 1/3 of the potatoes and 1/2 of the onion in lightly greased 13x9-inch baking dish. Sprinkle with 1 teaspoon of the sage mixture and 1/3 of the cheese. Repeat layers. Top with remaining potatoes, sage mixture and cheese.
Stir broth and cream in medium bowl with wire whisk until well blended. Pour evenly over potatoes.
Bake 1 hour or until potatoes are tender and top is golden. Let stand 5 minutes before serving.