1-Preheat oven to 350F: Preheat oven to 350F. Line an 8×8-inch pan with aluminum foil and spray with cooking spray. Lining your pan is highly recommended for ease of cleanup due to the stickiness of the caramel; set pan aside.
2-In a large microwave-safe mixing bowl, add: In a large microwave-safe mixing bowl, add the butter and heat on high power to melt, about 90 seconds.
3-Add the brown sugar, vanilla, and whisk: Add the brown sugar, vanilla, and whisk until smooth.
4-Add the flour, oats, baking soda, optional: Add the flour, oats, baking soda, optional pinch salt, and stir until combined. Mixture will be quite thick.
5-Add half of the mixture to the: Add half of the mixture to the prepared pan (just eyeball it), and smooth it with spatula or the back of a spoon, to create an even, smooth, flat layer; set remainder aside.
6-Bake for 10 minutes: Bake for 10 minutes. While it bakes, make the caramel sauce.
7-In a large microwave-safe mixing bowl, combine: In a large microwave-safe mixing bowl, combine the caramels* (see Notes below for caramel options), cream, salt, and heat on high power in 60-second bursts to melt caramels, stirring after each burst. It will likely take about 4 to 5 minutes total to melt; heat until mixture can be stirred smooth. Alternatively, combine caramels and cream in a medium saucepan, and heat over medium-low heat to melt, stirring nearly continuously, until mixture can be stirred smooth.
8-After 10 minutes, remove pan from the: After 10 minutes, remove pan from the oven and evenly sprinkle with the chocolate.
9-Slowly and evenly pour caramel sauce over: Slowly and evenly pour caramel sauce over the chocolate.
10-Evenly crumble reserved oatmeal-brown sugar mixture over: Evenly crumble reserved oatmeal-brown sugar mixture over the top.
11-Return pan to oven and bake for: Return pan to oven and bake for about 15 to 18 minutes (I baked 16 1/2), or until edges are lightly browned and center is bubbling slightly.
12-Allow bars to cool completely in the: Allow bars to cool completely in the pan before slicing and serving, giving the molten caramel time to firm up. This can take up to 4 hours, or overnight, at room temperature. You can speed it up by placing pan in fridge with a sheet of foil over the top to prevent fridge smells. If you don’t wait for bars to cool completely, they’ll be a literal hot mess. They’ll taste fine (don’t burn yourself), but they won’t slice neatly with clean cuts.