Step 1 Preheat the grill to a medium heat.

Step 2 Blanche the spinach for 30 seconds until it has wilted, then remove from the heat. Drain completely and squeeze in a teatowel to remove as much water as possible, then chop it roughly. Place in a bowl and stir through 2 tbsp Bearnaise sauce, mustard and 30g grated cheese. Stir until well combined and set aside.

Step 3 Heat a large frying pan. Butter both sides of the sourdough slices and place them butter side down in the pan until golden.

Step 4 Spoon the spinach over the uncooked side of one slice of bread, then generously fold slices of DukesHill smoked salmon over the top.

Step 5 Place the other slice of sourdough on top. Dollop another spoonful of bearnaise sauce over the top of the bread, before adding the remaining 30g grated cheese. Place the sandwich on a baking tray lined with parchment paper and grill the whole sandwich on medium until the cheese has melted and the bread is golden and crispy.

Step 6 While the sandwich is grilling, fry the egg and season well. Once the sandwich is grilled, remove it from the pan. Top with the fried egg and serve immediately.