Cut the bread and place on a wire rack to dry out a little as you prepare the batter.
Whisk the egg to blend. Melt 3 tablespoons of the butter in a saucepan or on the stovetop and allow to cool slightly. Whisk the sugar, salt and spices into the egg. When the butter has cooled slightly, slowly drizzle it in to the egg, whisking all the time. A little at a time, add the flour to the egg mixture to make a smooth thick paste. After it is all added, slowly blend in the milk and finally the vanilla. Whisk until just smooth and set aside.
Heat the remaining butter in a large skillet over medium heat. Dip a slice of the bread in the batter and allow to soak for 30 seconds, no more. Remove from the batter and allow the excess to drip off, back into the bowl. Place the battered slice in the skillet. Repeat with the remaining slices. Cook until golden on one side and then flip to brown the other. Serve immediately–a fresh squeeze of lemon juice and a good dusting of powdered sugar is traditional.