Bring a large pot of salted water to a boil. Cook the macaroni according to package directions. Drain and reserve.
Heat a small pan of salted water. Cook the broccoli until crisp tender (about 2 minutes). Rinse under cold water to stop the cooking. Chop into ½” pieces. Reserve.
Heat a large saucepan over medium low heat. Add butter and, whisking constantly, stir in the flour taking care the flour doesn’t brown. Continue to cook for 2 minutes.
Whisk in the milk. It will thicken as it gets hot. Whisk constantly; any lumps will smooth out. Cook for 5 to 7 minutes. Mixture will bubble and thicken. When it no longer changes in consistency, it’s done.
Stir in cheese. Season to taste with salt and pepper. Stir in pasta, broccoli and chicken. Spread into a 9” x 9” pan. Sprinkle with the breadcrumbs and press them into the surface. Cool completely (at least 2 hours). Cut into 6 squares.
Courtesy of PastaFits.org