Make the dough: In a mixing bowl, beat the softened butter, granulated sugar, and brown sugar until creamy and light, about 2 minutes. Add the egg and vanilla, and mix until smooth.

Combine dry ingredients: In a separate bowl, whisk the flour, baking soda, baking powder, and salt. Add the dry mixture to the wet ingredients and mix just until combined.

Fold in the mix-ins: Stir in the chocolate and crushed graham crackers. The dough should be soft but not sticky. If it’s very sticky, chill 10–15 minutes.

Prep the air fryer: Line the air fryer basket or tray with parchment made for air fryers or cut a piece with holes to allow airflow. Lightly spritz with oil to prevent sticking.

Portion the dough: Scoop 2-tablespoon mounds and roll into balls. Place 2–3 inches apart in the basket. Gently press each ball to about 1/2-inch thick so they cook evenly.

Air fry the base: Air fry at 320°F (160°C) for 5–6 minutes, until the edges look set but the centers are still soft. Work in batches to avoid crowding.

Add the marshmallows: Quickly open the basket and press a marshmallow half (cut side down) into the center of each cookie. If you like extra graham texture, sprinkle a pinch around the marshmallow.

Finish cooking: Return to the air fryer and cook 1–2 more minutes at 350°F (175°C) until the marshmallows are puffed and lightly toasted. For deeper color, add 30 seconds, watching closely.

Cool briefly: Let cookies rest in the basket 2 minutes to set, then transfer to a rack. Sprinkle with flaky sea salt if you like contrast.

Serve: Enjoy warm for maximum gooeyness. The chocolate and marshmallow will be soft and melty.