What you'll need is:
3/4 cup unsalted butter (don't worry, I've used regular butter before and it's just fine)
1 1/2 cups light brown sugar
1/2 cup dark brow sugar (if you don't have both kinds of brown sugar, just use what you have. (not white sugar though) I've done it and once again, it's just fine)
2 large eggs
1 large egg yolk
1 1/2 tsp vanilla extract
2 tsp baking powder
1 1/4 cups all purpose flour
1 tsp salt
1 cup chopped pecans
Preheat your oven to 350'
Get out a 13x9 casserole dish and line it with parchment paper. Yes, go out and purchase parchment paper (I'm talking to you Clare!!). It will make your life so much easier. Trust me.
In a sauce pan, melt your butter. Then add all of the brown sugar.
Stir it all together and keep stirring, over a medium heat, until everything is all melted and smooth. This will take a couple of minutes and it will start to resemble caramel
You might be tempted to dip your finger in there cuz it looks so good. But don't. It's really hot! (been there, done that).
Take the pan off the burner. If your counter is slippery, set the pan on a towel so it won't slide.
In a small bowl, whisk together the eggs, the egg yolk, and vanilla
Now....I couldn't take a picture of this next step because if I paused in my stirring, my egg mixture would've tuned into scrambled eggs. No one wants scrambled eggs in their blondies. Right? What you're gonna do is, add a small amount of the eggs to the melted brown sugar (which is still hot!), while quickly whisking it in before it "cooks" thus keeping it from scrambling. Then add another small amount, while whisking and then adding more and whisking all the while, until all the egg mixture is whisked into the brown sugar.
Is your arm tired yet? Bummer cuz you have a little more stirring to go. Not much. We're almost done so don't worry.
Now combine your flour, baking powder and salt in a small bowl. Stir the flour into your brown sugar mixture