• Whisk flour, sugar and salt in a large bowl.
• Add cubed and chilled butter to the flour mixture, using your finger tips rub the butter into the flour until it resembles bread crumbs. 
• Add ice water by spoon. Mix gently until the crust comes together. Don't add too much water. 
• Transfer the dough to the counter, shape it into a disk and wrap it in a plastic wrap. Chill in the fridge for one hour. 

Meanwhile, make the filling:

• Wash and dry the apples. Then slice them thinly and place them in a large bowl. 
• Mix the sliced apples with cranberries, brown sugar, walnuts, cinnamon, ginger and lemon juice. Set aside. 

Make the galette:

• Preheat the oven to 350F. Line a baking sheet with parchment paper. Set aside. 
• Take the crust out of the fridge and place it on the counter. 
• Tape a large piece of parchment paper on the counter. unwrap the crust and place it on the parchment paper. Cover with another piece of parchment paper. 
• Using a rolling pin, roll out the crust to ⅛" thickness. Carefully transfer it to the baking sheet. It's ok if it's bigger than the baking sheet, we will fold the edges. 
• Fill the middle of the crust with the apple filling, don't use the juice that the apples have released by now. Leave two inches from the edges. 
• Gently start folding the edges inside to cover a little bit of the apples. 
• Whisk the egg and brush on the edges of the crust. Sprinkle wit granulated sugar. 
• Bake in the oven for 25-35 minutes until the crust is golden brown and the apples are baked. 
• Cool the galette on the counter for 15-20 minutes before slicing. Serve with vanilla ice cream if desired.