Preheat the oven to 220c/200c fan/gas 7/425f

Place the flatbread on a non stick baking sheet

Mix together the crème fraiche, mustard, two thirds of the cheese and a small pinch of salt and spread evenly over the flatbread

Place the pancetta on the flatbread and crack an egg onto the centre, sprinkle over the remaining gruyere and season with some freshly ground black pepper

Transfer to the oven and cook for approximately 8-10 minutes until the white has set but the yolk is still runny