Heat oven to 350 degrees

Line 8" pan with parchment allowing it to extend over sides

Combine caramels and evaporated milk in a small saucepan over low heat until caramels are melted and mixture is smooth, stirring frequently

Mix flour, oats, brown sugar, baking soda and salt in a large bowl

Cut in cold butter by hand or with a pasty cutter until mixture is crumbly

Press half of this mixture into the bottom of prepared pan and bake for 10 minutes

Remove from oven and sprinkle chocolate chips over crust

Drizzle caramel mixture over chips to cover, and top with nuts if using

Sprinkle remaining crumb mixture over top and press very lightly.

Bake for 25 minutes or until golden brown

Allow to cool completely before removing from pan and slicing into bars