Preheat oven to 350. Line a 9x13 pan with foil and spray well with nonstick spray.
In a large bowl, combine flour, brown sugar, quick oats, and baking soda. Stir in melted butter until completely mixed in. Press 3/4 of mixture into pan and bake for 9 minutes.
Spread apple slices evenly over crust.
In a small pan, heat caramel and flour over medium heat until it starts to bubble. Remove from heat and pour over apple slices. Sprinkle Butterfinger pieces over the top, and top with remaining crust mixture, crumbling evenly over bars.
Bake for 20 minutes or until golden brown. Remove and let cool to room temperature before covering with foil and chilling completely.