Cut jalapenos in half lengthwise and remove seeds. Place jalapenos on an ungreased baking sheet. Broil 4-in. from the heat for 4-6 minutes on each side or until lightly blistered. Cool slightly.
In a small bowl, beat cream cheese and cheddar cheese until blended. Stir in onions. Spoon into pepper halves.
Place the flour, egg whites and bread crumbs in separate shallow bowls. Coat jalapenos with flour, then dip in egg whites and coat with crumbs. Place on a greased baking sheet; sprinkle with salt and pepper. Bake at 350° for 18-20 minutes or until lightly browned.
For dip, in a small bowl, combine all ingredients. Serve with poppers. Yield: 2 dozen (2 cups dip).