Heat oven to 350. Grease and flour an 8- or 9-inch square pan.
Mix all ingredients except those for the Orange Sauce in a medium bowl with electric mixer on low speed 30 seconds, scraping bowl constantly. Beat on medium speed 3 minutes, scraping bowl occasionally. Pour into pan.
Bake 30 to 35 minutes or until toothpick inserted in center comes out clean.
For sauce, mix sugar and flour in 2-quart saucepan. Gradually stir in water. Cook over medium heat, stirring constantly with wire whisk, until mixture thickens and boils. Boil and stir 1 minute; remove from heat. Stir in butter and orange juice. Serve immediately over warm pudding.