I listed the vanilla extract as optional because rumor has it Levain Bakery doesn't add vanilla in theirs. However, you can add in 1 tsp. vanilla. I've tested and it's delicious!
Feel free to make the cookies smaller in size. May need to bake for a minute or so less since they are smaller.
My original recipe also called for 3 cups of chocolate chips but after several people made it, 3 seemed to be TOO much. 2 cups seems to be PLENTY for most people.
No cake flour? No problem. I tested this recipe using a "homemade cake flour" recipe. It resulted in a very similar product and I thought it was better than the 100% All-Purpose cookie.
To make homemade cake flour, you'll need 14 Tbsp. All-purpose flour and 2 Tbsp. corn starch. Mix these together and sift them twice to get them fully mixed and aerated. This will make ~1 cup flour. You only need 3/4 cup for this recipe.
To measure out the flours, use the spoon and level method. Spoon the flour into your measuring cup and be sure it's leveled. Do not scoop the flour out of the container/bag with your measuring cup because you could end up with 50% more than you need. Spoon and level by using a spoon to scoop the flour into the measuring cup and use the back of a knife to level off the top of it.
GLUTEN FREE: Replace both the All-Purpose flour and Cake flour with: Bob's Red Mill Gluten Free 1-to-1 Baking Flour . I tested this & cookies are very similar in taste and appearance and a great option for those who need a GF cookie.