Preheat your air fryer: Set it to 400°F (200°C) for 3 minutes. A hot basket helps the bologna brown fast.
Prep the bologna: Score each slice with three small slits around the edges or a shallow X in the center. This prevents curling into a bowl and helps it cook evenly.
Air fry the bologna: Place slices in a single layer in the basket.
Cook for 3–4 minutes, flipping halfway, until edges are browned and slightly crisp.
Toast the bread: While the bologna cooks, spread one side of each bread slice with a thin layer of butter or mayo. After removing the bologna, place bread butter-side down in the basket and air fry 1–2 minutes until lightly toasted.
Melt the cheese: Lay the bologna back in the basket, top with cheese, and heat for 30–60 seconds until the cheese softens. Alternatively, place the cheese on the bread to melt gently.
Assemble: Spread mustard on the non-buttered side of the bread.
Add bologna with melted cheese, pickles, and any extras you like. Top with the second slice of bread.
Optional final toast: For a grilled-cheese-style finish, return the assembled sandwich to the air fryer for 1 minute to unite everything and crisp the exterior slightly.
Serve hot: Slice in half and dig in while the edges are still crisp and the cheese is gooey.