In 2 quart bowl, mix first 4 ingredients and refrigerate until cold, about half an hour.
Cut bread into 1" - 2" cubes. To prevent dryness, keep bread covered until ready to serve.
Serve dip in bowl in center of large platter with bread cubes and veggies (if used) arranged around the sides.
If you want to get fancy you can remove the center of one loaf, leaving sides and bottom to form a bowl. Spoon dip into new cavity in loaf and cube the bread removed in addition to the other loaf. Be sure to drape bread lightly with towel or plastic wrap to prevent dryness until ready to serve.