Cut the baguette in half lengthwise, then cut each half into 2 equal pieces to make 4 pieces total.

Rinse the mushrooms briefly, pat them completely dry with paper towels, and slice them thinly if not already sliced.

Heat a skillet over medium heat and add the butter.

Add the sliced mushrooms to the skillet and cook, stirring occasionally, for 5 to 7 minutes until most of the moisture has evaporated and the mushrooms are lightly browned.

Season the mushrooms with salt, pepper, and dried oregano, stir, and cook for 30 seconds more, then remove from heat.

Divide the cooked mushrooms evenly over the cut sides of the baguette pieces, pressing them lightly so they adhere.

Sprinkle the shredded cheese evenly over the mushrooms on each baguette piece.

Place the baguette pieces in a single layer in the air fryer basket, cheese side up; work in batches if needed.

Air fry at 360°F for 6 minutes, or until the cheese is fully melted, lightly golden, and the edges of the baguette are crisp.

Remove from the air fryer and serve hot with ketchup or your favorite sauce.