2/3 cup plain Greek-style yogurt
1 garlic clove, halved
Kosher salt
2 tablespoons unsalted butter, divided
2 tablespoons olive oil
3 tablespoons chopped leek (white and pale-green parts only)
2 tablespoons chopped scallion (white and pale-green parts only)
10 cups fresh spinach (10 ounces)
1 teaspoon fresh lemon juice
4 large eggs
1/4 teaspoon kirmizi biber (Turkish chili powder), or 1/4 teaspoon crushed red pepper flakes and a pinch of paprika
1 teaspoon chopped fresh oregano