Sift together dry ingredients; flour, icing sugar, hazelnut, salt
Add very cold butter cubes and rub the mixture between your hands until it becomes a sand like consistency
Add egg into the mixture and mix with your hands just until the dough comes together
Knead with the palm of your hand for a minute or two (do not over knead and do not use mixer) just until the dough becomes smooth
If the dough is too warm and sticky, place it into the fridge for 10-15 minutes first. Otherwise continue with rolling the dough out into 2mm thickness between two Silicone baking mat. Place the dough into the freezer for 15 min in between the two Silicone baking mat.. Do not remove the mat at this point Take the dough out from the freezer, remove the top of the silicone mat and using one of the Perforated tart rings, cut out 8 circles - this will be the bottom of your tart crust. Carefully move the dough circles with the help of an Offset spatula and place them into the rings one by one If at any point the dough gets too warm to work with, pop it back into the freezer for 5 minutes. You might need take the dough in and out of the freezer many times depending on the temp of your kitchen. It is extremely important to work with a dough which is cold enough to be able to handle (so not sticky) but not too cold which would result in breaking it
Cut 8 long stripes out of the dough, this will be the side of the tart
Carefully place the stripes into the ring one by one. Press each stripe onto the ring so it sticks to it
Place the Perforated tart ring with the pastry dough in them into the freezer for 1 hour Pre-heat oven to 160C / 320F
After 1 hour take the pastry dough with the rings on them out and trim them with a sharp knife
Bake for 20 min then carefully remove the rings and bake for another 5 -10 min until golden brown. Let them cool on the Perforated "air" baking mat before filling