Season both sides of the salmon with a good pinch of salt and black pepper.

Heat ½ tablespoon oil in a large deep (preferably non-stick) pan over medium-high heat. Once hot, add the fillets and leave to fry until they build up a nice golden crust on the bottom. Flip them over and continue frying for a minute longer, then add the butter and baste them until they're almost cooked through the centre (about 2 ½ - 3 minutes each side depending on the thickness of the fillets). Make sure you undercook them slightly as they'll continue cooking whilst they rest. Remove them from the pan and cover them with foil in a bowl.

Lower the heat to medium and add the leek to the leftover fat in the pan. Gently sweat it down until soft and just starting to turn golden. Stir through the lemon zest and orzo, then stir in the stock and 2 teaspoon lemon juice. Bring to a simmer, then reduce the heat slightly and cook until the orzo is al dente with the sauce thickened. Stir in the parmesan and Boursin, then stir in the spinach and resting juices from the salmon. Check for seasoning and adjust if needed.

Once the spinach has wilted, add the salmon back on top to warm it through, then serve up with a squeeze of lemon juice and fresh parsley (optional).