In a large saucepan over medium heat, combine granulated sugar and water, stirring gently to blend. Allow the mixture to dissolve for about ten minutes until bubbly.

Once the caramel reaches the desired color, remove it from heat. Carefully whisk in room-temperature unsalted butter until fully melted.

Incorporate vanilla extract and kosher salt into the caramel mixture, whisking until completely smooth.

In a large mixing bowl, whisk together old-fashioned oats, all-purpose flour, baking soda, and a pinch of kosher salt until well blended.

Cream together light brown sugar and room-temperature unsalted butter using a hand mixer on medium speed until fluffy and light in color.

Add the large eggs and a splash more of vanilla extract to the creamed mixture. Beat on medium speed until smooth and creamy.

Gradually add the dry oat-flour mixture to the wet ingredients, one cup at a time. Mix until just combined and thick.

Grease a 9x13-inch baking dish generously with butter or baking spray. Spread about two-thirds of the prepared cookie dough evenly in the dish.

Sprinkle the milk chocolate chips evenly over the cookie dough layer. Drizzle the cooled caramel sauce over the chocolate chips.

Use flattened dollops to place the remaining cookie dough gently on top of the caramel, leaving some openings.

Preheat your oven to 350°F (175°C) and bake the assembled cookie bars for 38 to 40 minutes, or until lightly browned.

Once baked, allow the bars to cool in the dish for thirty minutes. Then, transfer them to the fridge and chill for one hour.