In a large mixing bowl, combine the 2 cups all-purpose flour, 1 1/2 tablespoon baking powder, and 1 teaspoon Kosher Salt. Mix well to evenly distribute the baking powder and salt throughout the flour.
Slowly fold in the 2 cups Greek yogurt to the dry ingredients. Mix until a dough forms.
With a rolling pin, roll out the dough on a lightly floured surface to about 1/4 inch thickness. Spread one-third of the butter evenly over the rolled-out dough. Fold the dough into thirds, like a letter, creating three layers. Cover the dough and place it in the refrigerator to chill for at least 30 minutes.
Roll out the dough on a lightly floured surface to about 1/4 inch thickness. Cut the dough into triangles. Starting from the wide end, roll up each triangle to form a croissant shape.
Brush the top of each croissant with an 1 large Egg
Preheat your air fryer to 350 degrees F (175°C) for about 3-5 minutes.
Place the croissant dough in a single layer in the air fryer basket. Set air fryer temperature to 350 degrees F (175°C) and set cook time for 10-12 minutes, or until they are golden brown and flaky.