Preheat your oven to 350°F (175°C). Grease a 9x13 inch baking pan or line it with parchment paper for easy removal.
In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar together until creamy and well combined.
Add the eggs one at a time, mixing well after each addition. Then, stir in the vanilla extract until fully incorporated.
In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Spread half of the dough mixture into the bottom of the prepared baking pan, pressing it down evenly.
Pour the caramel sauce over the layer of dough, spreading it evenly with a spatula.
Take the remaining dough and crumble it over the caramel layer to cover it as much as possible. Don't worry if it isn't perfect; some caramel can peek through.
Sprinkle the sea salt over the top of the bars.
Bake in the preheated oven for 30-35 minutes, or until the top is golden brown and a toothpick inserted comes out clean (it may have a few caramel bits).
Allow the bars to cool completely in the pan on a wire rack before cutting into squares or rectangles.
Notes
Serve the bars on a decorative plate, garnished with a drizzle of caramel sauce and a sprinkle of sea salt on top for an attractive finish.