Open-faced hot turkey sandwich smothered in rich gravy over white bread is the ultimate comfort food protein meal. This classic diner dish is a family favorite, especially after the holidays.
Melt unsalted butter in a saucepan over medium heat. Add flour and whisk constantly for 2 minutes to form a blond roux without browning.
Slowly pour in low-sodium chicken broth while whisking vigorously to avoid lumps; bring mixture to a boil, then reduce heat to low and simmer for 5–10 minutes until a thick, silky gravy forms.
Season the gravy with kosher salt, black pepper, and onion powder. Taste and adjust seasoning if needed, keeping heat on low to hold warm.
Lay two slices of white sandwich bread on each plate. Arrange the sliced cooked turkey breast evenly over the bread.
Generously ladle hot gravy over the turkey and bread. Serve immediately while sandwich is piping hot, optionally garnishing with extra black pepper.