Preheat oven to 400°. Heat a large cast iron skillet to to medium heat and add your oil.
Toss in your chicken and cook until cooked through and browned, about 4 minutes per side.
Transfer to a cutting board and let sit for 5 minutes. Cut into 1-inch cubes and set aside.
Whisk your flour and ⅔ cup milk to the pan; bring to a boil over medium-high heat. Gradually whisk in the flour milk mixture. Return to a boil and cook stirring occasionally, until thickened, about 2 to 3 minutes.
Stir in broccoli and return to a boil until broccoli in tender, about 2 minutes. Stir in chicken and cheese and salt, pepper, and garlic powder. Sprinkle the onions on top.
Transfer the skillet to the oven and bake for 10 minutes until the top is browned and bubby. Let cool 5 minutes and devour.
Notes
How can my kids help?Have them pound your chicken; if need be. Also have them sprinkle on the fried onions, with supervision, of course :)