Gratin of Two Potatoes

By polledl

Grandma enjoyed making variations to her recipes. Sometimes she would leave the skins on the sweet potatoes. Prior to boiling the potatoes, she scrubbed them under cold running water. Grandma knew that the skins contained the greatest concentration of nutrients.
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Ingredients

• 2 large baking potatoes (about 1 1/4 pounds)
• 2 large sweet potatoes (about 1 1/4 pounds)
• 1 tablespoon unsalted butter
• 1 large sweet or yellow onion, thinly sliced and separated into rings
• 2 teaspoons all-purpose flour
• 1 cup canned chicken broth
• 1/2 teaspoon salt
• 1/4 teaspoon white pepper
• 3/4 cup freshly grated Parmesan cheese

Details

Preparation time 55mins
Cooking time 80mins

Preparation

Step 1

1Place baking potatoes in a large saucepan with water to cover and bring to a boil; boil 10 minutes. Add sweet potatoes; return to a boil. Simmer, uncovered, until tender, about 25 minutes. Drain; cool potatoes under cold running water.
.2Melt butter in nonstick skillet over medium-low heat. Add onion and cook until tender, 10 to 13 minutes, stirring occasionally. Add flour; cook 1 minute, stirring frequently. Add chicken broth, salt and pepper. Bring to a boil over high heat. Reduce heat and simmer until the sauce thickens, about 2 minutes.
.3Preheat oven to 375F. Grease 13x9-inch baking dish with butter. Peel potatoes; cut crosswise into thin slices. Layer half of baking and sweet potato slices in prepared dish. Spoon half of onion mixture evenly over potatoes. Repeat layering. Cover. Bake until heated through, about 25 minutes.
.4Preheat broiler. Uncover potatoes; sprinkle evenly with Parmesan. Broil until Parmesan is bubbly and golden brown, about 5 minutes.