Combine first 5 ingredients in a shallow dish, stirring mixture well.
Coat a large nonstick skillet with cooking spray; place over medium heat until hot. Dip bread slices, one at a time, into egg mixture, coating well.
Place 4 bread slices in skillet, and cook 6 to 8 minutes on each side or until browned. Remove from skillet, and keep warm. Repeat with remaining bread and egg mixture.
Place peaches on a baking sheet coated with cooking spray. Combine brown sugar and cinnamon; sprinkle over peaches. Broil 5 1/2 inches from heat (with electric oven door partially opened) 4 to 5 minutes or until sugar mixture is bubbly.
Combine sour cream, maple syrup, and vanilla in a small bowl; stir well.
To serve, place 2 slices French toast and 4 peach quarters on each serving plate. Top peaches with sour cream mixture.