In a big bowl sieve in your flour and add your salt and baking powder and give it a light stir.
Cut your butter into small fragments (easier to mix the softer but no too soft or melted)add your egg and egg yolk and natural yogurt and sugar.
Using your hand you mix the mixture toghter in a squashing like motion until it forms a ball of dough , (if you find it too wet add more flour if you find it too dry add more yogurt).
You can now put the dough into the fridge while you make the apple filling.
Peel the apples from the skin and dice them into small cubes.
In a saucepan boil 1/2 cup of water with the sugar and add half the cinnamon.
when the water reaches boiling you can throw in the apples and cover them in the rest of the cinnamon,mixing the apples you might get too much water you can pour some out into a seperate bowl at the side.
Letting the apples soften and boil for about 10 mintues or untill they arent hard and can mush easily setting them aside to cool.
Taking your dough out the fridge you can flour an area of your worktop preparing it for the dough.
Cut about 3/4 of your dough and roll it out to the size of your pan laying it down and poking small holes at the bottom when in the pan.
Scoop out all your apple filling and spread it out eavingly in the pan.
Rolling out any residue dough and using a ruller to cut our 1inch wide rectangles to fit your pan.
You should have aproximentally 8 of these stripes laying half of them horizontal and the rest vertical.
Cut off and excess of the sides and sprinkle the sugar and optional egg wash and put in the oven for about 40min.