I would like to know what the weight/volume conversion is for the 2 1/8 cups all purpose flour in this recipe -- in other words, how many ounces f...

Sarah, if you haven't already, you might want to post your question in the Comments section of the recipe itself. It's possible the authors of the recipe receive email copies of posts there. You can also send them an email through their Profile: just click on the envelope icon next to the "Follow" button on their profile page.

i've never seen sifting enter the picture unless the directions are to sift. MOST people (i think) use the :fluff up flour, dip and level the top method. There's a great baking cookbook author- alice medrich- who talks about and teaches alot of these issues in her books. really helpful books, and terrific recipes. I have a few but mostly use Bittersweet.

Btw 4-5 oz per cup, depending on the author. America's test kitchen uses 5 oz while King Arthur flour always uses 4 1/4 oz per cup of AP flour. There is no "correct" way to measure flour and each cook does it differently, no matter what anyone says.

Experiment and pay attention to the sugar:butter:flour ratio, reducing sugar and butter for a less sweet, slightly chewier cookie with less spread. You can also checkout http://www.lafujimama.com/2010/03/nestlefoodies-toll-house-chocolate-chip-cookies-better-than-the-original-shhh-dont-tell/ for another variation of the toll house cookie recipe.