Preheat the oven to 350 degrees. Grease a 9x13 baking pan with nonstick spray and set it aside.
Add the brown sugar, butter, and cookie butter to a large bowl and whisk them together until light and creamy, a couple minutes.
Add in the eggs and vanilla and stir together until combined.
Add in the flour, baking powder, and salt and stir it into the wet ingredients until just combined.
Pour in half the white chocolate chips, and half the chopped cookie pieces.
Scoop the batter into the prepared pan and spread the top evenly using a rubber spatula.
Sprinkle the remaining chocolate chips, and cookie pieces over the top of the batter.
Bake for 20 to 25 minutes, or until a toothpick can be inserted and comes out clean.
Allow the bars to cool for at least 10 minutes, before cutting and serving.