LAYER 3 cups of the bread cubes, 1 cup of the cheese, chicken and the red pepper in greased 2-quart oblong baking dish; top with remaining 3 cups bread cubes.
BEAT eggs, milk and mustard with wire whisk until well blended; pour over bread layer, being careful to evenly moisten the bread. Sprinkle with remaining 1/2 cup cheese; cover. Refrigerate at least 2 hours or overnight.
PREHEAT oven to 325°F. Bake, uncovered, 45 minutes or until knife inserted in center comes out clean. Let stand 10 minutes before serving.