In a medium saucepan, melt the butter over medium heat.
Whisk in the all-purpose flour and cook for 2 to 3 minutes, stirring constantly, until the mixture is golden and bubbly to form a roux.
Gradually whisk in the chicken broth, ensuring no lumps form.
Bring the mixture to a simmer and cook for 5 minutes, stirring frequently, until the gravy thickens.
Add the finely chopped cooked chicken breast to the gravy and stir to combine.
Remove the saucepan from heat and stir in the plain Greek yogurt until smooth.
Season the gravy with garlic powder, onion powder, black pepper, and salt. Stir well.
Return the saucepan to low heat and warm the gravy gently for 2 to 3 minutes without boiling.
Remove from heat and serve immediately over your favorite dishes.