Step 1 – Make the crust
In a bowl, combine flour and salt. Cut in the cold butter until the mixture resembles coarse crumbs. Add ice water a tablespoon at a time until the dough comes together. Flatten into a disc, wrap, and refrigerate for at least 30 minutes.

Step 2 – Prepare the potatoes
Thinly slice potatoes using a mandoline or knife. Toss with olive oil, garlic powder, salt, and pepper. Set aside.

Step 3 – Roll out the crust
On a lightly floured surface, roll the chilled dough into a 12-inch circle. Transfer to a parchment-lined baking sheet.

Step 4 – Assemble the galette
Sprinkle most of the shredded cheddar in the center, leaving a 2-inch border. Layer the potatoes in overlapping circles. Top with remaining cheese and chives.

Step 5 – Fold and bake
Fold the dough edges over the filling, pleating as needed. Brush crust with beaten egg. Bake at 400°F (200°C) for 35–45 minutes until the crust is golden and potatoes are tender.

Step 6 – Cool and serve
Let cool slightly before slicing. Garnish with extra chives or sea salt and serve warm or at room temperature.