In a medium bowl, whisk milk, eggs, brown sugar, cinnamon, and vanilla.
Dip bread into egg mixture and lightly press down to coat both sides. Let excess drip off before placing onto skillet.
Melt butter in a large skillet over medium heat. Transfer bread to skillet and cook on each side for 3-4 minutes, or until golden brown. Repeat with rest of bread slices.
Serve immediately with powdered sugar, butter, and maple syrup, if desired.