How To Make Overnight French Toast:
Add brown sugar, flour, cinnamon and salt to a bowl and mix well. Use a pastry blender to cut in butter until it’s in small chunks. Mix well.
Sprinkle topping on top of french toast and continue to bake, or cover and refrigerate overnight until ready to bake.
Note: You can cut in cold butter with a pastry blender as well. It will just take a little more elbow grease and extra time to mix.