Preheat the oven to 350°F, and spray a 13 x 9-inch baking dish with nonstick cooking spray.
In a medium-size sauce pot, bring the chicken broth to a boil. Add the rice, cover, and reduce heat to low. Let simmer for 15–20 minutes, just until all the water has been absorbed. Remove from heat and let cool for 5 minutes before fluffing with a fork.
Melt the butter in a large stockpot over medium-high heat.
Add the chicken to the pot, and sauté for 5 minutes, browning well on all sides. Add the diced onion to the pot, and sauté for an additional 2 minutes.
Stir the flour into the pot, coating the chicken and onions, and let cook for 1 minute.
Stir the milk, salt, white pepper, and onion powder into the pot, and bring to a simmer. Reduce heat to low, and let simmer for 2 minutes.
Remove the pot from the heat, and stir in the broccoli, 1 cup Cheddar cheese, and cooked rice. Transfer to the prepared baking dish, and top with the remaining ½ cup of cheese.
Bake for 25–30 minutes, or until cheese has melted and sauce is bubbly hot. Let cool for 7 minutes before serving. For 100 calorie portions, slice into 32 sections by cutting 4 rows by 8 rows.