Step 1

Place noodles in a large skillet. Pour broth over the noodles. Layer chicken, then broccoli over the noodles.

Step 2

Whisk milk, mayonnaise, flour, dry mustard, garlic powder, salt and pepper in a medium bowl. Pour over the broccoli.

Step 3

Bring to a simmer over medium-high heat. Reduce heat to maintain a simmer, cover and cook, stirring once or twice, until the noodles and chicken are cooked through, 15 to 18 minutes.

Step 4

Meanwhile, position rack in upper third of oven; preheat broiler.

Step 5

When the casserole is done, sprinkle cheese on top and broil until lightly browned, about 3 minutes.