Preheat oven to 350 and line a 9x13 pan with parchment sprayed with oil spray.
Whisk together flour, baking powder and salt in a bowl. In another bowl whisk together the brown sugar, butter, eggs and vanilla.
Fold the flour mix into the wet ingredients and then fold in the white chocolate chunks.
Spread in an even layer in your pan. If using my caramel sauce, if it has been in the fridge, microwave about 20-30 seconds until is somewhat liquid so you can spoon over the top. If using caramels, microwave the caramels and cream for 30 seconds, stir and continue heating in 30 second increments and stirring until smooth.
Drop spoonfuls of caramel over the batter and use a knife to swirl it in a little. Bake for 25-30 minutes, rotating halfway through, until the edges are browned and the center feels set when you touch it. Cool for 20 minutes, then place in the fridge for 20 minutes before cutting to make easier to cut. Cut into 20 squares or less if you want larger squares.