Melt the butter in a large skillet over medium high heat.
Make the custard
Whisk together the eggs and milk, then add the maple syrup and cinnamon.
Dip and cook
Add the custard to a shallow bowl, and dip slices of bread in the custard, making sure to flip several times. Let the excess drip off and cook in batches 2-3 minutes each side until golden brown and cooked through.
Serve
Top with butter, maple syrup and powdered sugar if desired.