Preheat your oven to 350 degrees.
Line a 9x13 pan with foil and spray the foil with nonstick spray.
In a medium bowl stir together the flour, oats, brown sugar, baking soda, and salt.
Stir in the melted butter until well blended.
Press HALF of this oat mixture into the bottom of the foil-lined 9x13 pan. Set the other half of the oat mixture aside.
Bake the crust in the oven for 8 minutes.
While the crust is baking, in a medium pan over low heat, melt the caramels and cream, stirring occasionally until smooth, then add in vanilla.
Remove the pan that has been baking in the oven and sprinkle with chocolate chips and walnuts.
Pour the caramel mixture over the top of the chips and walnuts.
Crumble the remaining oat mixture evenly on top of everything and press down gently on the oat mixture.
Return to the oven and bake for an additional 20 minutes.
Let the bars cool completely before slicing.