Preheat the oven to 350 degrees. In a large mixing bowl, combine the flour, oats, brown sugar, salt and soda. Add melted butter and mix well. Place 2/3 of this mixture into a 9x13 pan that's been sprayed with cooking spray. Bake for 10 minutes.
While the crust is baking, microwave the caramel bits (or unwrapped caramels) and heavy cream in a microwave safe bowl. Start with 30 seconds, stir, then continue in 15 second intervals stirring in between, until the caramels are completely melted and cream is incorporated.
When the crust is done, sprinkle the bag of chocolate chips on top, followed by the nuts, then the melted caramel. Add the remaining crust mixture evenly on top. Bake for 15 more minutes.