Preheat an oven at (175 celsius / 350 fahrenheit / gas mark 4).
In a large microwave safe bowl, melt the butter in 30 second increments, once melted, let it cool to room temp.
While the butter cools, grab all of your leftover candy or chocolate and chop it up, you should have about a cup of candy for this recipe. (Pro Tip: if you’re using any caramel candy you can just add them in whole, unless they are really big!)
Now, add both sugars, vanilla and salt into the butter and mix well.
Next, crack in the egg and whisk together.
Fold in the flour and baking powder, it might seem like too much flour but, just keep mixing and it will come together.
Finally, add in your chopped chocolate and mix well.
Spread the dough evenly into a 8x8 inch lined baking pan.
Bake the cookie bars for 25 - 30 minutes or until they are golden brown and set on the edges and have puffed up. The middle will still be pretty underbaked, but they will continue to cook as they cool!
Once fully cool, with a sharp knife cut the cookie bars into 9 large bars or 16 small bars and enjoy!