Put the olive oil and 1 tbsp butter in a dish in your air fryer. Add the garlic, onions, smoked paprika and black pepper. Set the air fryer to 180C/355F and cook for 5 minutes.
Stir, add the mushrooms and dot the last of the butter on top. Put back in the air fryer and cook for a further 5 minutes. Set the dish aside.
Butter each slice of bread with 1 tbsp of butter. Place two slices of bread in the air fryer, butter side down.
Sprinkle with half the cheddar and mozzarella cheese, layer on the mushrooms, then sprinkle half of the remaining cheese on top.
Top each toastie with the remaining slices of bread, butter side up, then sprinkle with the last of the cheese and a final pinch of smoked paprika.
Set the air fryer to 160C/320F and bake for 10 minutes until the bread is golden and the cheese is melted.