Having baked 200 to 300 batches of these in the last couple of years (I baked them for a social table at church); I've modified the recipe again. Because I'm an engineer, I've tried to describe the process is such a way as to make it repeatable, where anyone can duplicate these.
Preheat oven to 325 degrees F.
1 cup white sugar
1 1/2 cups light brown sugar (300 grams)
1 3/4 teaspoons baking powder
2 teaspoons real vanilla
2 sticks (8 ounces) real butter
3 1/2 cups white flour (420 grams)
6 ounces semi-sweet chocolate chips
11 1/2 ounces Ghirardelli milk chocolate chips
2 large eggs
Soften the two sticks of butter (8 ounces) in the microwave oven.
Add baking powder on one side of the bowl and vanilla on the other (we don't want the baking powder to contact too much moisture at this moment).
Flour compresses easily. Scooping flour into the cup from the container can result in 30% more by weight than by spooning it from the container into the measuring cup. I've found as much as 10% difference by brands.
The best way is to measure--get the weight of the cup empty then add 120 grams of flour for each cup.
Search online for "measure flour" and you can find lots of advice.