Which of the following options is a breakfast specialty at Denny's?

French Toast is a breakfast specialty at Denny's because it is a classic breakfast item that combines slices of bread soaked in a mixture of eggs and milk, then cooked on a griddle until golden brown. This dish is often served with toppings such as syrup, powdered sugar, or fresh fruit, making it a popular choice for those looking to enjoy a sweet breakfast experience.

In contrast, Spaghetti Carbonara, Beef Tacos, and Caesar Salad are not traditional breakfast items and are typically associated with lunch or dinner menus. Denny's focuses on a wide variety of breakfast options, and French Toast fits perfectly within their offerings, resonating with customers seeking classic morning dishes.