Add sifted flour and salt into a large bowl. Make a well in the centre of the flour and crack in the eggs. Start whisking the eggs being careful to mix in any flour from around the side of the bowl.
Slowly add the milk while you continue whisking. When all the milk has been added, whisk once again and make sure you have a smooth batter with a runny consistency.
Mix the pre-melted butter to the mixture.
Spray a frying pan with Frylight and place over a medium heat. Wait until Frylight is clear. Pour in some batter mix and tilt and turn the pan until evenly covered. Cook for a couple of minutes then turn (or flip!). Cook for another minute or so until the pancake is firm and well cooked in the centre.
Repeat until all pancake mix is used.
Make the filling:
Gently heat the butter in a pan until melted and stir in the flour. Gradually add the milk, whisking constantly until you have a smooth thickened sauce. Add half of the grated cheese and stir through. Season with salt and pepper and set aside.
Spray a large frying pan with Frylight and place over a medium heat. Wait until Frylight is clear and then add onion and mushrooms. Cook for 5-10 minutes until starting to brown, add garlic and cook for a further few minutes.
Ensure the spinach has been squeezed of excess water and add to the pan. Mix to combine.
Pour sauce into the pan, add nutmeg and stir together.
Fill each pancake with the filling and roll up. Place into a baking dish and pour over any remaining sauce. Sprinkle over the remaining cheese and the grated parmesan. Bake in the preheated oven for 15 minutes until bubbling and lightly brown on top.