In a medium bowl, whisk together your dry ingredients ( flour, baking soda and salt) and set aside.
In the bowl attached to a stand mixer, place the butter, white sugar and brown sugar. Start the mixer on low speed and cream them together until they are fully incorporated.
Add in the eggs, beating until smooth, then mix in the vanilla until completely mixed in as well.
Stop the mixer and then add the dry ingredients, beating on medium speed until fully incorporated.
Mix in the pecans and chocolate chips by hand.
Take a jelly roll pan (which is basically a standard baking sheet that has a raised edge) and grease it well. Spread the mixture through the pan evenly. IF you want THICK bars, then use a 9x13 pan ( this is how I make them, they are so good!)
If you used a jelly roll pan, bake them for 15-17 minutes and start checking to see if they are done. If you are making thick and chewy cookie bars, bake in the oven for 25-30 minutes- do not overbake! You want them slightly under-baked so that they are chewy.