Place chicken breasts in an oven-safe baking dish.
Drizzle with olive oil and season with garlic powder, onion powder, oregano, salt, and pepper.
Bake for 25-30 minutes, or until cooked through.
Meanwhile, in a medium saucepan, combine chicken broth, heavy cream, and Dijon mustard. Simmer over medium-high heat, stirring occasionally, until mixture is slightly thickened, about 8 minutes.
Remove chicken from oven and top with mozzarella cheese. Top with chopped broccoli florets. Pour sauce over chicken and broccoli.
Sprinkle with cheddar cheese.
Bake for 15 minutes, or until cheese is melted and bubbly.
Serve immediately.
Interesting Facts
The dish was first created at the Divan Parisien restaurant in New York City in the 1930s.
The original version of the dish was made with white sauce, but today, many recipes call for a creamier sauce made with cream and Dijon mustard.
It is popular in the United States, especially in the Midwest and Northeast.