Preheat your oven to 350°F (175°C) and lightly grease a 9x13 inch casserole dish with cooking spray.
In a medium saucepan, combine the brown rice and vegetable broth. Bring to a boil, then reduce heat to low, cover, and simmer for about 45 minutes or until the rice is tender and broth is absorbed.
While the rice is cooking, bring a large pot of salted water to a boil. Add the broccoli florets and blanch for about 3 minutes until bright green. Drain and immediately transfer to a bowl of ice water to stop the cooking process. Once cooled, drain again and set aside.
In a large mixing bowl, combine the cooked rice, blanched broccoli, shredded cheddar cheese, sour cream, milk, diced onion, minced garlic, onion powder, garlic powder, black pepper, and salt. Stir until well mixed.
Pour the mixture into the prepared casserole dish, spreading it evenly.
In a small bowl, combine the breadcrumbs and olive oil, mixing until the breadcrumbs are coated. Sprinkle the breadcrumb mixture evenly over the casserole.
Bake in the preheated oven for 30-35 minutes, or until the top is golden brown and bubbly.
Remove from the oven and let cool for a few minutes before serving.
Notes
Serve warm, garnished with a sprinkle of fresh parsley for color. For added texture, consider drizzling a little extra melted cheese on top right before serving.