With the back of a large spoon, press or indent the 4 slices of bread to make a well, however, make sure the edges are kept intact to hold the custard.
Mix the yogurt and egg yolks together, with a sprinkle of sugar, reserving the majority of the sugar for later use.
Add in the vanilla and gently whisk together.
Evenly divide and spoon the custard mixture onto each slice of bread surface.
Sprinkle with the reserved sugar
Bake in Air Fryer for approximately 5-10 mins. or until golden brown and the sugar has caramelized.