01 - Dissolve yeast in warm milk with 1 tsp sugar. Let stand 5 minutes until foamy and activated.
02 - Combine flour, remaining sugar, and salt in a large bowl. Add melted butter, egg, and yeast mixture. Stir until blended, then knead 5-8 minutes until smooth and elastic. Shape into a ball, cover, and refrigerate 1 hour.
03 - Place cold butter between parchment sheets. Pound and roll into a 6x6 inch square. Refrigerate until firm.
04 - On floured surface, roll dough into 12x12 inch square. Center butter block on dough. Fold dough over butter, sealing edges completely to create a pocket.
05 - Roll dough into 16x8 inch rectangle. Fold into thirds like a letter. Rotate 90°, roll out, and fold again. Wrap and refrigerate 30 minutes.
06 - Repeat rolling and folding process. Refrigerate another 30 minutes to relax gluten.
07 - Roll dough into 16x10 inch rectangle. Cut into 8 triangles. Roll from wide end to tip, curving slightly. Place on parchment-lined tray.
08 - Cover and let rise in warm, draft-free place 1-2 hours until puffy and doubled in size.
09 - Preheat air fryer to 320°F. Brush risen croissants with egg wash for golden finish.
10 - Place 2-4 croissants in basket without overcrowding. Cook 8-10 minutes until deep golden and cooked through. Repeat with remaining batches.
11 - Cool slightly on wire rack. Serve warm.