Toss the chicken with garlic powder, salt, and pepper. Heat olive oil in a 10-inch skillet over medium heat. Add chicken breast and cook for about 3 minutes until it's no longer pink on all sides. Add garlic to skillet and cook for 30 seconds more.
Stir in rice and chicken broth. Bring to a boil, reduce to a simmer, and cover. Cook for 20-25 minutes, stirring occasionally, until liquid is absorbed.
Remove pan from heat and place baby spinach on top of the rice. Cover and let sit for 5 minutes.
Remove lid and stir well. Stir in cream or milk, and serve.