In a large skillet, cook onions in butter over medium heat for 15-20 minutes or until golden brown, stirring frequently. In a large bowl, whisk the eggs, sour cream, salt and caraway seeds. Stir in the onions and ham.
On a lightly floured surface, roll the dough into a 16-in. x 11-in. rectangle. Transfer to a greased 15-in. x 10-in. x 1-in. baking pan; build up edges slightly to form a crust. Spread with onion mixture. Bake at 350° for 25-30 minutes or until golden brown. Cut into squares; serve warm. Yield: 2 dozen.