Heat a large skillet over medium-high heat and add a drizzle of oil.
Add the cubed chicken, season with salt and pepper, and cook for 5-6 minutes until lightly golden. Remove and set aside.
In the same skillet, add the chopped onion and cook for 2 minutes until softened. Stir in the minced garlic and cook for 30 seconds until fragrant.
Stir in the rinsed rice, then pour in the chicken stock and water. Bring to a gentle boil.
Reduce heat to low, cover, and simmer for 15 minutes, stirring occasionally.
Stir in the chopped broccoli and return the cooked chicken to the skillet. Cover and cook for another 5 minutes until the broccoli is tender and the rice is fully cooked.
Pour in the milk and 1 ½ cups of shredded cheddar cheese, stirring until melted and creamy.
Remove from heat, sprinkle the remaining ½ cup of cheese on top, and cover for 2 minutes to let it melt. Serve warm.