Leek and Potato Galette

Instructions

1. Prepare the leeks
   Clean the leeks thoroughly by slicing them lengthwise and rinsing under cold water to remove any grit. Pat dry and thinly slice. In a large skillet, melt the butter with 1 tablespoon olive oil over medium heat. Add the leeks and cook gently for 10-12 minutes until soft but not browned. Add the minced garlic and cook for 1 more minute. Season with salt, pepper, and a pinch of nutmeg. Remove from heat and allow to cool slightly.
2. Prepare the potatoes
   Slice the potatoes very thinly (about 3mm thick), using a mandoline if available. Place in a bowl and toss with the remaining tablespoon of olive oil, salt, and pepper.
3. Prepare the pastry
   Preheat the oven to 200°C (390°F). Line a baking sheet with parchment paper. Roll out the puff pastry on a lightly floured surface to form a rectangle about 35cm x 25cm. Transfer to the prepared baking sheet. Score a 2cm border around the edge of the pastry with a knife, being careful not to cut all the way through. Prick the center area with a fork.
4. Assemble the galette
   Spread the crème fraîche over the center of the pastry (inside the scored border). Sprinkle half of the grated Gruyère over the crème fraîche. Spread the cooled leek mixture evenly on top. Arrange the potato slices in overlapping rows over the leeks. Sprinkle with fresh thyme leaves and the remaining Gruyère cheese. Brush the border with beaten egg.
5. Bake the galette
   Bake in the preheated oven for 30-35 minutes, until the pastry is puffed and golden brown and the potatoes are tender. If the top starts to brown too quickly, cover loosely with foil.
6. Serve
   Remove from the oven and let rest for 5 minutes. Sprinkle with additional fresh thyme leaves and a light drizzle of olive oil. Cut into squares or slices and serve warm or at room temperature.