To make the Pastry:

1. In the bowl of a food processor, place the flour, sugar and butter and pulse about 10-15 times. The pieces of butter should be about the size of a pea.
2. Add the egg and pulse a couple of times.
3. Add 2-3 tablespoons of water. The dough should just stick together.
4. Turn the dough out onto some plastic wrap and form into a round and place in the refrigerator for at least 30 minutes.

To make the Filling:

1. Preheat the oven to 400° F oven and line a baking tray with parchment paper.
2. Peel apples, the chop into quaters. Slice out the cores, then chop into small slices. Place the slices into a bowl and add the egg, sugar, flour, cinnamon and lemon juice.

Assembling the galette:

1. Roll out the pastry dough into a 12-14 inch circle.
2. Place the dough on the baking tray.
3. Arrange or scatter the apples in the center of the disk of dough, leaving a 1-2 inch ring around the edge. Folld the edge over the apples, leaving the center uncovered.
4. Bake for 45 minutes until the edges are golden and crisp.
5. Allow 5 minutes before cutting.