Place the butter in a large saucepan over medium heat, stirring to melt. Slowly whisk in the flour, salt, and pepper and stir till smooth and thick (about 1-2 minutes).
Slowly whisk in the chicken broth until smooth. Increase the heat to high, whisking until thick (about 2 minutes). Add the sour cream, Ranch seasoning, garlic salt, and cooked chicken. Stir together well.
Place a nice pile of rice in the middle of your plate and pour some of the gravy over the rice. Top with all kinds of delicious toppings and enjoy!