Preheat the oven to 350°F (175°C).
In a large bowl, mix the Dijon mustard, honey, garlic powder, and chicken broth until well combined.
Add the chicken thighs to the mixture, ensuring they are well coated. Let it sit for about 10 minutes to marinate.
In a large casserole dish, layer the cooked rice evenly on the bottom.
Sprinkle the frozen vegetables over the rice, creating a colorful layer packed with nutrients.
Place the marinated chicken thighs on top of the veggies and rice. Pour the remaining marinade over everything.
Cover the casserole dish with aluminum foil and bake for 25 minutes.
Remove the foil, sprinkle shredded cheddar cheese over the top, and bake for an additional 10-15 minutes until the cheese is melted and bubbly, and the chicken is cooked through.
Let it cool for a few minutes before serving to allow the flavors to set.