01 - Preheat the air fryer to 350°F for 3 minutes.
02 - Unroll the croissant dough and separate into 4 triangles. Spread a thin layer of Dijon mustard onto each triangle if desired.
03 - Layer 1 slice of roast beef, 1 slice of ham, and 1 slice of cheese onto the wide end of each triangle.
04 - Roll up each croissant starting from the wide end, tucking in the sides to seal the filling inside.
05 - Place croissants seam-side down in the air fryer basket, ensuring they don't touch each other.
06 - Brush lightly with softened butter if desired for extra golden color.
07 - Air fry for 7 to 8 minutes until golden brown and crispy. Let cool for 2 to 3 minutes before serving.