In a medium saucepan, melt the butter over medium heat. Whisk in the flour and cook for 2–3 minutes, stirring constantly, until the mixture is golden and bubbly.
Stir in the crushed beef and chicken bouillon cubes until fully dissolved.
Slowly pour in the water while whisking continuously to avoid lumps. Continue whisking until smooth.
Bring the mixture to a gentle simmer and cook for 5–7 minutes, stirring frequently, until thickened.
Stir in black pepper and adjust seasoning to taste.
Pour warm gravy over mashed potatoes, fried chicken, biscuits, or your favorite comfort foods.