- Preheat oven to 350°F (175°C).
- Use your fingers to snap off woody ends of asparagus about 1 inch (2.5 cm) from bottom and discard. Slice asparagus into 1 inch (2.5 cm) pieces. Slice the green onions and mushrooms and dice the red peppers. Set aside.
- Heat the butter in a large skillet over medium heat. Add the prepared vegetables and sauté briefly, only a minute or so to coat with the butter. Do not overcook as they will be baked next.
- Coat a 9 x 13 inch (20 x 30 cm) baking pan with vegetable spray. Scatter vegetables across bottom of baking pan.
- Cut cooked chicken and bread into 1.5 inch (4 cm) cubes. Mix with vegetables in bottom of pan.
- Whisk together eggs, milk, Dijon mustard, dried Italian dried herbs and freshly ground black pepper. This can be done quickly in the blender or food processor. Slowly pour the egg mixture over the ingredients in the pan.
- Grate cheese. Spread evenly over top of the chicken bread pudding followed by the chopped parsley and a sprinkle of paprika. Cover and refrigerate overnight.
- Bake 45-60 minutes or until set and a knife inserted in the center comes out clean. Let stand 10 minutes before serving.
Although this casserole is usually made ahead and refrigerated overnight you can also bake it right away.