In a bowl, beat cream cheese until smooth. Add sour cream; mix well. Fold in crab, cheese and onions. Cut the top third off each loaf of bread; carefully hollow out bottoms, leaving 1-in. shells. Cube removed bread and tops; set aside. Spoon crab mixture into bread bowls. Place on baking sheets. Place reserved bread cubes in a single layer around bread bowls. , Bake, uncovered, at 350° until the dip is heated through, 45-50 minutes. Garnish with green onions if desired. Serve with assorted fresh vegetables, crackers and/or toasted bread cubes.