01 - Preheat oven to 350°F. Line a 9x13-inch baking pan with parchment paper, allowing overhang for easy removal.
02 - Beat softened butter, brown sugar, and granulated sugar in a large bowl until light and fluffy. Add eggs individually, mixing thoroughly after each. Incorporate vanilla extract.
03 - Whisk flour, baking soda, and salt in a separate bowl. Gradually incorporate into the wet mixture, mixing until just combined.
04 - Fold semi-sweet chocolate chips into the dough until evenly distributed.
05 - Press half the dough evenly into the prepared pan. Drizzle caramel sauce over the base layer, then distribute remaining dough in dollops and gently spread to cover.
06 - Bake for 28-32 minutes until golden brown and set. Cool completely in the pan on a wire rack.
07 - Melt butter in a medium saucepan over medium heat. Stir in brown sugar until dissolved. Bring to a gentle boil and cook for 2 minutes, stirring constantly.
08 - Pour in milk, stir, and return to a gentle simmer. Remove from heat and let cool for 5 minutes.
09 - Whisk in powdered sugar, vanilla, and salt until smooth and spreadable. Adjust consistency with additional milk if needed.
10 - Spread caramel frosting evenly over cooled bars. Let set for 15-20 minutes before cutting into squares.