Potato Leek and Feta Galette

Ingredients

• 1/2 teaspoon salt
• 1/2 + 1/8 cup butter (cold and cut into small cubes)
• 1/4 cup water (ice cold and more if needed)
• 1 egg yolk
• 1 tablespoon olive oil (plus more for drizzling)
• 1 leek (white and pale-green parts only, thinly sliced)
• 1/2 cup crumbled feta cheese
• 1/4 cup heavy cream
• 2 garlic cloves (minced)
• 1/4 teaspoon black pepper
• 1/2 bunch fresh dill (divided)
• 2 Yukon Gold potatoes (thinly sliced)
• 1 egg (beaten)