Preheat the oven to 350 degrees. Spray a 9" by 9" pan with cooking spray, line it with a piece of parchment that extends up two sides of the pan, spray the parchment, and set aside.

Place the butter in the largest bowl your microwave will fit (this prevents butter splattering), and microwave it on high for 7-8 minutes, until the butter smells nutty and brown bits have sunk to the bottom of the bowl. To do this on the stove, turn the heat to medium and melt the butter in a small saucepan until the butter exhibits the above nuttiness and brown bits.

Meanwhile, whisk the flour, baking powder and salt together in a medium sized bowl. Add the pecans and chips to the bowl and toss the add-ins with the flour. Set aside. Place the sugars in a large bowl and set aside.

Add the sugars to the bowl you microwaved the butter in, or if you used a saucepan, transfer the butter to a large bowl and add the sugars. whisk until fully incorporated.

Add the eggs and yolk one at a time, whisking gently after each addition. Add the vanilla and gently whisk again. Add the flour mixture to the bowl and using a rubber spatula, very gently fold the flour into the butter, sugar and eggs. Do not over-mix. Transfer the blondie batter to the prepared pan and use the rubber spatula to smooth the top.

Sprinkle the Maldon sea salt (if using) over the top of the blondies, place the pan in the oven and bake for 26 to 28 minutes, until the top is lightly browned and crackly (I'd say pull them sooner rather than later as they can get dry and crumbly very quickly).

Remove the pan from the oven and let cool on a rack until room temp, or until just cool enough to keep their shape if you want to eat them gooey and melty. Lift the blondies out of the pan by the parchment paper overhang and slice. Slice and serve with vanilla ice cream.