Prep oven and pan. Preheat the oven to 350°F (175°C) with the rack in the center position. Then, line a 9x13-inch baking dish with aluminum foil, allowing it to overhang by a few inches to create handles for easy removal later. Don't forget to spray the foil generously with non-stick cooking spray.
Make the oatmeal layer. Mix together the flour, oats, brown sugar, baking soda, and salt in a big bowl. Then, melt the butter and add it to the dry ingredients. Stir everything together until it becomes crumbly. After that, put away 3 cups of the mixture to the side for later. Press the rest firmly into the bottom of the baking dish you prepared.
Add the chocolate and caramel layers. Unwrap the caramels and put them in a microwave-safe bowl. Pour the cream or half and half over the caramels. Microwave on medium power for about 5 minutes, stirring halfway through, until the caramels are completely melted and the mixture is smooth. Pour the melted caramel evenly over the oatmeal layer in the baking dish. Sprinkle the chocolate chips evenly over the caramel layer.
Top and bake. Evenly sprinkle the remaining oatmeal mixture over the chocolate chips. Put it in the oven for 30 minutes or until the top turns golden brown. Take it out of the oven and let it cool on a wire rack.
Serve. When the bars are fully cooled, grab the foil handles to take them out of the baking dish. Move them to a cutting board and cut them into 24 bars.