Preheat oven to 350 degrees and grease a 8" or 9" square baking dish or line with parchment pan. An 8" dish will yield slightly thicker bars.
In a large bowl, combine 1 cup flour, oats, sugar, melted butter, baking soda, and salt. Mix to form crumbs. Divide mixture in half. Press half of the mixture in the bottom of the prepared baking dish. Bake for 10 minutes.
Sprinkle chocolate chips and nuts (if using) in an even layer over baked mixture. For the Caramel Sauce: Heat caramels and cream in a pot on the stove whisking and stirring until smooth. You can also do this in a microwave safe bowl and heat in intervals, stirring in between. Drizzle caramel filling over chocolate chips.
Sprinkle remaining oat mixture on top trying to cover most of the caramel. Bake for 15-20 minutes or until golden brown. Sprinkle with some kosher salt if desired. Cool completely before cutting. This takes a really long time. You can speed these up by placing the bars in the fridge. Serve and store bars at room temperature in an airtight container.
Notes
This can be doubled and baked in a 9x13 baking dish.There's another way to make the caramel sauce. If using store bought caramel sauce, in a small bowl, mix 3 tablespoons flour with 1/2 cup store bought caramel sauce to thicken it.I've also made these without adding flour to the caramel mixture. Depending how thick your caramel sauce is you may not have to add the flour.Source: My mother-in-law's friend Peggy Rothmeier.