Step 1: In a large bowl, whisk together the flour, granulated sugar, and salt. Cut in the cold butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs with some pea-sized pieces of butter remaining.
Step 2: Gradually add ice water, one tablespoon at a time, mixing until the dough just starts to come together. Form into a disk, wrap in plastic, and refrigerate for at least 1 hour.
Step 3: Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Step 4: In a medium bowl, toss the sliced pears and cranberries with brown sugar, cornstarch, cinnamon, ginger, and cardamom until evenly coated.
Step 5: On a lightly floured surface, roll out the chilled dough into a 12-inch circle. Transfer the dough to the prepared baking sheet.
Step 6: Arrange the fruit mixture in the center of the dough, leaving a 2-inch border around the edges. Fold the edges of the dough up and over the fruit, pleating as you go.
Step 7: Brush the folded dough with the beaten egg and sprinkle with turbinado sugar.
Step 8: Bake for 40-45 minutes, or until the crust is golden brown and the fruit filling is bubbling. Let the spiced pear cranberry galette cool slightly before slicing.