In a greased 4- or 5-qt. slow cooker, layer tortillas, whole green chiles, chili con carne and 1 cup cheese.
In a small bowl, whisk eggs, milk, biscuit mix, salt, pepper and, if desired, pepper sauce until blended; pour into slow cooker. Top with chopped green chiles and tomatoes.
Cook, covered, on low until a thermometer reads 160°, 3-4 hours, sprinkling with remaining cheese during the last 30 minutes of cooking. Turn off slow cooker; remove insert. Let stand 15 minutes before serving. If desired, top with sour cream.