2 teaspoons margarine 1 ½ cups finely chopped red onions 8 ounces cream cheese, softened ¼ to 1/3 cup finely crumbled bleu cheese ¾ cup heavy cream 1 tablespoon dried thyme leaves, crushed ½ teaspoon salt 2 pounds baking potatoes, (about 4 medium)
Preheat oven to 350 degrees. Grease 11" x 7" baking dish. Melt butter in large skillet over medium heat. Add onions; cook and stir about 5 minutes or until soft. Remove from heat; set aside to cool in small bowl.
Beat cream cheese in large bowl with electric mixer at medium speed until fluffy. Add bleu cheese; beat until blended. Beat in cream, thyme and salt at low speed until mixture is smooth. There will some small lumps. Add cooled onions; beat until blended.
Peel potatoes, then grate 1 potato into cheese mixture. Fold into cheese mixture with rubber spatula. Repeat with remaining potatoes, one at a time.
Pour mixture into prepared baking dish; cover with foil. Bake 45 minutes. Uncover; bake 15 to 20 minutes more until crisp around the edges.
Turn oven to broil. Broil casserole 3 to 5 minutes until golden brown.
