Whisk the egg well, then add the milk, vanilla, and a little sugar and cinnamon. Mix until combined.

Spread pistachio butter evenly over one side of a slice of toast.

Place another slice of toast on top and press the two slices together firmly so they stick.

Gently dip the toast sandwich into the egg and milk mixture, coating all sides.

Fry the toast on all sides in oil (or butter) until golden brown.

Remove from the pan and roll the toast in the cinnamon-sugar mixture.