Combine the Dry Ingredients: Mix the all-purpose flour and salt together in a large bowl until evenly combined.
Cut in the Cold Fats: Add the cold cubed butter and vegetable shortening to the flour mixture.Use a pastry cutter or two knives to cut the fats into the flour until the pieces are about the size of peas. Form the Dough: Add the ice water 1 tablespoon at a time, mixing gently with a fork until the dough comes together and forms a ball.
Shape the Pastry: Turn the dough onto a lightly floured surface and shape it into a disk. Lightly flour the dough, then roll it into a large circle approximately 12 inches across. Create a Round Pastry: If desired, use a large bowl to cut the rolled dough into a more precise round. The original recipe notes that the dough can also be left free-form.The recipe makes enough dough for a double crust, so some pastry will remain. Transfer the Dough: Place the pastry circle onto a baking sheet lined with parchment paper.
Preheat the Oven: Preheat the oven to 400°F and make sure the baking sheet is prepared with parchment.
Prepare the Apples: Core the apples and slice them thinly.
Season the Fruit: Place the sliced apples in a bowl and toss them with the granulated sugar, cinnamon, and lemon juice until the slices are evenly coated.
Arrange the Apples: Starting near the outer portion of the pastry, arrange the apple slices in overlapping circles, working inward toward the center. Leave at least 1 inch of pastry uncovered around the edge for folding. Fold the Pastry: Bring the exposed pastry edge up around the apples, folding and pleating the dough as you work around the galette.
Add the Cranberries: Scatter the cranberries evenly over the arranged apples.
Dot with Butter: Distribute the small cubes of butter over the fruit filling.
Bake the Galette: Bake at 400°F for about 45 minutes, until the pastry is golden and the apples are tender.
Cool Before Serving: Allow the finished galette to rest before serving so the baked fruit and flaky pastry can settle.