Start by making the pastry, put the butter and sugar in the bowl of a stand mixer, fitted with the paddle attachment and beat until they are creamed together and light and fluffy.
Gradually add the eggs and beat until they become emulsified with the butter and sugar, you may need to scrape the sides down with a spatula.
Finally add the flour and mix gently, until it starts to come together. Then turn the dough out onto a piece of clingfilm and shape into a rectangle and cover with the clingfilm and place it in the fridge for at least 2 hours. This can be made up to 3 days in advance.
Next make the nappage, place the water and liquid glucose into a saucepan and bring to a boil.
Mix together the sugar and pectin in a small bowl, then add it to the boiling mixture and cook for about 2-3 minutes, whisking all the time.
Transfer to an airtight container and leave to cool before placing it in the fridge. This can be kept in the fridge and used within a week.
Take a 20cm by 4cm loose-bottomed cake tin, take the pastry out of the fridge and place it on a floured surface, roll out the pastry.
When the pastry is rolled out big enough to cover the tin lay the pastry over the tin, pressing it into the sides and base of the tin.
Leave the excess pastry overhanging the edge, this will help with shrinkage. Trim the pastry a little if necessary. Place the pastry case in the fridge for 30mins to chill a little.
Pre-heat the oven to 180C Fan/200C and line the pastry case with baking parchment and baking beans. Blind bake the pastry for 15 minutes. Then remove the baking beans and baking parchment and return to the oven for 5 minutes.
Check the pastry over to see if it needs any of the cracks patching use some raw pastry and fill the holes. Take the egg wash and brush it all over the pastry and bake for another 15 minutes.
When the pastry is golden, remove it from the oven.
To make the frangipane, cream the butter and sugar together in the bowl of a stand mixer with the paddle attachment. When they are light and fluffy add in the egg and beat until combined. Finally add the flour and ground hazelnuts mixing until fully incorporated.
Pour the frangipane into the base of the cooled baked tart case and smooth it with a small palette knife so that it is spread in an even layer.
Take the apple slices and arrange them in any pattern you like on top of the frangipane. I fanned them out in a circular pattern. just be aware that if you don't place the apples close together the frangipane will burn through.
Preheat the oven to 170C Fan/190C and place the tart in the oven to bake for 45mins - 1 hour. After 30 mins cover the top of the pie with a piece of tin foil to stop the apple burning. After 45mins check if the tart is cooked.
When the tart is cooked, bring it out of the oven and glaze it immediately with the light fruit nappage. To do this, heat the nappage in a pan until it becomes liquid again and then using a pastry brush, spread it all over the apples to give them a lovely shine.
Leave the tart to cool in its tin and then remove it from the tin when it is completely cooled. Decorate with crystallised hazelnuts if using.