Preheat oven to 350 degrees and butter a 9×9 inch square baking pan.
In a small saucepan over medium heat, melt butter with brown, sugar and maple syrup. When the sugar is dissolved, transfer the mixture to a large heatproof bowl.
Stir in flour, oats, graham cracker crumbs, salt, and cinnamon, until all ingredients are covered in the butter mixture.
Press the oat/butter mixture into the bottom of the prepared baking pan.
Sprinkle chopped Milky Ways and mini marshmallows over the top.
Bake granola bars for 15 minutes. Let cool in pan before slicing into squares or bars.