Prepare frozen waffles in the oven rather than heating them in the toaster or microwave. The key step is to sprinkle them with water while they're still frozen.
Private chef Gianna Stanley says drizzling a few drops of water on the waffles before going in the oven "reintroduces moisture and will help you get an even better texture."
Sprinkling water on your waffles will make them nice and crispy without leaving them dry, but ensure that you don't get them too wet, or they won't crisp up.