For sauce, mix 2 1/4 c fresh cranberries, 3/4 c water, and 1/2 c sugar in saucepan. Bring to boil over medium-high heat, stirring frequently. Reduce heat and simmer, stirring, until mixture is thickened. 5 minutes. Cool. Preheat oven to 375 degrees f. Bring 2 lb peeled, diced sweet potatoes and enough lightly salted water to cover to boil in large saucepan. Reduce heat and simmer, covered, until tender, 10 minutes. Drain, return potatoes to pan. Cook over high heat, stirring, 1 minute. Transfer to large bowl; add 1/2 tsp salt and 1/4 tsp pepper. With electric mixer on medium speed, beat potatoes until smooth. Cool. Spread 1 1/2 c potatoes in 1 quart souffle dish. Layer top with 1 c sauce, remaining potatoes in and remaining sauce. Cover with foil. Bake until heated through, 35 to 40 minutes.