Preheat your oven to 200 degrees Celsius.
Crack the egg into a bowl and whisk with a fork.
Season the egg with salt and pepper.
In another bowl, add the flour.
In a third bowl, crush the tortilla chips to a powder and stir in the cajun seasoning and panko breadcrumbs.
Line a baking tray with greaseproof paper and spray well with 1 kcal spray.
Pound or flatten each chicken breast to an even thickness so that it will cook. You could also cut the breast into thinner strips instead if they are very thick.
Dip the breasts in the bowl of flour to fully coat it on all sides.
Next dip it in the egg mixture.
Finally dip it in the cajun crumb mixture and add the breast to the baking tray.
Repeat with all the chicken breasts.
Spray each chicken breast well with 1kcal spray.
Bake in the oven for 25 minutes until crispy and cooked throughout.
Meanwhile, mix the sour cream and sriracha sauce in a small bowl to make a the spicy sauce.
Toast each bun and top with some fresh lettuce, crispy chicken and the spicy sauce.