Start by finely slicing your potatoes, you could do this using a potato slicer or a knife. If using a knife make sure your slices are wafer thin! Then pop your potato slices into a bowl and wash gently with water.
Pat dry, lay out on a lined baking tray and cover with cooking spray, salt and pepper, and cheese. Bake at 190C for around thirty minutes, or until soft.
Dice your onion, and in a pan on a medium heat, drizzle olive oil and throw in your mince to brown along with your onion. Once this has began to brown, add in your salt and pepper, and nutmeg.
Remove your potatoes from the oven and gently spread your boursin cheese all over. Then, add on top your mince and onions mix. Once done, you can begin to roll your potatoes. Use the parchment paper to help you achieve a tight roll.
Brush on the yolk of one egg and bake at 200C for a further fifteen minutes or until golden.