01 - Dissolve yeast in warm milk with 1 tsp sugar. Let stand 5 minutes until foamy.
02 - Combine flour, remaining sugar, and salt. Add melted butter, egg, and yeast mixture. Knead 5-8 minutes until smooth. Form into ball, cover, and refrigerate 1 hour.
03 - Pound cold butter between parchment into 6x6 inch square. Refrigerate until firm.
04 - Roll dough into 12x12 inch square. Center butter block and fold dough over, sealing edges.
05 - Roll into 16x8 inch rectangle. Fold into thirds. Rotate 90°, roll, and fold again. Refrigerate 30 minutes.
06 - Repeat rolling and folding process. Refrigerate 30 minutes.
07 - Roll dough into 16x10 inch rectangle. Cut 8 triangles. Roll from wide end to tip. Place on parchment-lined tray.
08 - Cover and let rise in warm place 1-2 hours until puffy.
09 - Preheat air fryer to 320°F. Brush with egg wash. Cook 2-4 croissants 8-10 minutes until golden. Repeat.