Galette Dough:

1) In a medium sized bowl, whisk together flour, sugar, and salt. Add in cubed butter and toss to coat.

2) Using a pastry cutter or your fingers, cut the butter into the flour mixture until it reaches pea or lentil size. Slowly drizzle in water and mix only until a shaggy dough forms.

3) Dump the dough out onto a piece of plastic wrap. Pull the plastic wrap to form the dough into a disc. Fully wrap and let rest in the fridge for at least 1 hour.

Filling:

1) Slice the apples into thin slices. Place in a large bowl. Add in the blackberries, sugar, cornstarch, and butter and stir to fully combine. Let macerate for 10-15 minutes.

Assembly:

1) Preheat the oven to 400ºF and line a baking sheet with parchment paper*. 

2) Dust a clean surface with flour and place rested dough onto the surface. Roll the dough into a 10-11 inch circle and transfer your circle onto the prepared baking sheet.

3) Using a slotted spoon, lay the apple mixture on top of the galette dough leaving a 3/4 inch border. Fold the leftover border over and brush with beaten egg.

4) Place galette in the oven and immediately turn the heat down to 375ºF. Bake for 45-50 minutes until the crust is golden brown and the filling is bubbling. Remove from oven and let fully cool.