Preheat the oven to 350°F. Line a 9x13 baking dish with parchment paper and spray with cooking spray, set aside.

In a medium-sized bowl stir together the flour, baking powder, and salt until combined, set aside.

In a large bowl whisk together the brown sugar, melted butter, eggs, and vanilla until smooth.

Add the dry ingredients to the wet and stir them together until there are no dry patches. Add 1 & ½ cups of the butterscotch chips and fold them in until evenly distributed.

Spread the batter into the prepared baking dish, I find it easier to do with moistened hands. Take a handful of the remaining butterscotch chips and sprinkle it over the batter for a pretty presentation.

Bake for 25-30 minutes until the top appears dry and set and a toothpick inserted into the center comes out clean.

Let them cool completely in the pan. Take the bars out using the parchment paper to help you lift them out. Cut into bars.

Place the remaining butterscotch chips into a microwave-safe bowl. Microwave in 15-second intervals, stirring in between until melted. Place the melted butterscotch into a piping bag or ziplock bag and cut a small piece of the corner off. Drizzle over the cut bars, let them set for about 20 minutes so the butterscotch on top solidifies, and serve immediately.