01 - Preheat the air fryer to 350°F for 3 minutes to ensure optimal cooking temperature.
02 - Unroll the croissant dough and separate into 4 individual triangles on a clean work surface.
03 - Spread a thin layer of Dijon mustard onto each triangle if desired, leaving edges clean for sealing.
04 - Place 1 slice of roast beef, 1 slice of ham, and 1 slice of cheese on the wide end of each dough triangle.
05 - Roll each croissant starting from the wide end toward the point, tucking in sides to enclose the filling completely.
06 - Place croissants seam-side down in the air fryer basket, leaving space between each piece for proper air circulation.
07 - Brush tops lightly with softened butter using a pastry brush for enhanced golden color and richness.
08 - Cook for 7 to 8 minutes until golden brown and crispy. Let rest 2 to 3 minutes before serving to allow filling to set.