Line your 9"x13" baking dish with tinfoil and lightly spray it with oil. Preheat the oven to 350 degrees.
Chop 1 1/2 cups of pecans and toast them in a small pan over medium-high heat. You'll know they're ready to go when you can smell the toasty nutty flavor, should only take 3-5 minutes. Remove from the heat and set to the side.
In a small saucepan add 2/3 cup of salted butter and cook over medium-high heat just until it starts to brown. Then turn down the heat and add 1 packed cup of dark brown sugar, 3/4 cup of maple syrup, and 2 tsp of vanilla. Stir until sugar is melted and everything is thoroughly combined.
In a separate bowl, whisk together 2 cups of flour, 1 tsp baking powder, 1/4 tsp baking soda, and 1/4 tsp salt. Stir in 1 cup of the toasted pecans and set to the side.
In your KitchenAid mixer fitted with the whisk attachment, add the two eggs and whip on high until a pale yellow and fluffy. While the mixer is still going on medium-low speed, slowly pour in the butter mixture. Whisk until combined.
Next, add in the flour/nut mixture in three separate batches, mixing thoroughly between each one. Once all the flour is incorporated, pour the blondie batter into the prepared baking dish and smooth it out evenly.
Place it in the oven on the middle rack and bake at 350 degrees for 25 minutes. If you're using a glass 9"x13" dish it will take 20-25 minutes, a stoneware baker will take 30-35. Use the toothpick test to know when they're done.