Remove a little of the oil then add the butter to the pan, once the butter has melted add the eggs. Season. Cook gently, folding and stirring, until just set. This will only take a minute, or less. Scoop out of the pan and set aside. Wipe the pan clean.
Heat a griddle pan over a medium, high heat. Place a tortilla on, scatter ¼ of the cheese over the entire tortilla. Then over one side of the tortilla scatter the jalapenos, spring onion, cooked chorizo and egg along with a ¼ of the chorizo, eggs and cheese onto one half of the tortilla, folding the other half on top. Toast for a minute on each side until golden and the cheese has melted. Repeat with the remaining three tortillas.