Preheat oven to 300 degrees.
In a non-stick skillet, melt butter over medium heat.
Add peach slices and sugar to the pan and cook until the peaches begin to soften (approximately 3 minutes).
Remove pan from the heat and put aside.
In a shallow bowl, whisk egg and milk together.
Reheat skillet and melt 1 Tbsp butter in skillet.
Soak two pieces of bread in the egg mixture and then place them on the skillet.
Arrange peach slices on top of the bread.
Soak the last two pieces of bread in the egg mixture and place them on top of the peaches.
Cook French toast at low-medium heat until golden brown, approximately 5 minutes per side.
Transfer French toast to a baking sheet and keep warm in the oven while you cook the rest.
When ready to serve, cut into fingers and sprinkle with a dusting of icing sugar and a splash of warm maple syrup.