Adjust oven rack to middle position and heat oven to 400 degrees.
Pulse bread and butter in food processor until coarsely ground. Set aside. Combine sugar and cinnamon in small bowl.
Melt butter in large nonstick ovensafe skillet over medium-high heat. Cook peaches, stirring occasionally, until they begin to caramelize, 8 to 12 minutes. Off heat, stir in 1 cup crumb mixture, sugars, lemon juice, vanilla, and salt.
Top peach mixture with remaining crumbs. Sprinkle with cinnamon sugar and bake until topping is golden brown and juices are bubbling, 20 to 25 minutes. Cool 10 minutes. Serve warm.