Preheat oven to 425*F (220*C). Heat up skillet over medium heat. Cut chicken up into cubes or thin slices. Place into skillet, sprinkle with salt and pepper and cook chicken thoroughly.
While chicken is cooking, cut baguette loaf in half and then cut lengthwise each half to make 4 pieces. Spread butter over crust and inner side bread. Place crust side up into oven and cook for 10 minutes, turn over and cook face down for 10 minutes or until lightly golden toasted.
Take bread out of oven, turn face upward and sprinkle as thickly or sparingly as you like over the 4 bread sections the green and red bell pepper slices, onion, and chicken.
Top with alfredo sauce, again as thickly or sparingly as you prefer. Place back in oven for 10 to 15 minutes until vegetables and sauce have time to heat up thoroughly.