Preheat the oven to 350F. Line an 8" x 8" pan with aluminum foil and spray with cooking spray.

In a large microwave-safe mixing bowl, add the butter and heat on high power to melt, about 60 seconds.

Add the flour, oats, baking soda, and stir.

Put about half of the mixture evenly in the prepared pan and lightly pat it down to make a flat layer.

Bake for 10 minutes. 

While it bakes, make the caramel sauce. I've used Kraft caramels before but they are hard to unwrap and I think Werther's tastes better.

In a large microwave-safe mixing bowl, combine the caramels and cream. Heat on high power in 60-second intervals to melt caramels, stirring after each burst. It takes about 4 to 5 minutes total to melt. 

Heat until the mixture can be stirred smooth. I've also done this on the stovetop stirring constantly over low heat until smooth. Which works but the microwave is easier.

Remove the pan from the oven and evenly sprinkle with the chocolate. Pour the caramel sauce evenly over the chocolates. 

Crumble the reserved oatmeal-brown sugar mixture over the top. 

Bake for about 16 to 20 minutes, or until edges are lightly browned and center is bubbling slightly.

Allow bars to cool completely in the pan before slicing and serving, giving the melted caramel time to firm up. After about three hours on the counter, I covered the bars with foil and put them in the refrigerator for one hour so that they were completely cool. Lift the bars out of the pan, remove foil and use a large knife to cut into squares. Sprinkle the bars very lightly with the Kosher or sea salt if desired.