1. Heat oven to 350°F. Grease bottom only of 8- or 9-inch square pan. In large bowl, beat cake ingredients on low speed 30 seconds. Beat on medium speed 2 minutes. Pour into pan.
2. Bake 44 to 49 minutes for 8-inch pan or 38 to 43 minutes or 9-inch pan until toothpick inserted in center comes out clean. Cool completely, about 1 hour.
3. In medium bowl, beat powdered sugar, 1/4 cup butter and 1 tablespoon of the orange juice with electric mixer on low speed until mixed. Add remaining orange juice, 1 teaspoon at a time, until creamy and smooth. Beat in 1 teaspoon orange peel. Spread frosting on cooled cake. Garnish with orange peel or mandarin orange segments.
1 Serving: Calories 340 (Calories from Fat 120); Total Fat 14g (Saturated Fat 8g, Trans Fat 0g); Cholesterol 85mg; Sodium 300mg; Total Carbohydrate 52g (Dietary Fiber 1g, Sugars 37g); Protein 2g Percent Daily Value*: Vitamin A 8%; Vitamin C 4%; Calcium 0%; Iron 8% Exchanges: 1/2 Starch; 3 Other Carbohydrate; 0 Vegetable; 2 1/2 Fat Carbohydrate Choices: 3 1/2
*Percent Daily Values are based on a 2,000 calorie diet.