M&M cookies

http://time.com/3179770/the-science-behind-baking-the-most-delicious-cookie-ever/

Chewy: Substitute bread flour for all-purpose flour.

My best guess is:

bread flour for all-purpose

less flour

all granulated sugar (I think)

both baking soda and powder

dough not chilled

Best guess was the joy of cooking chocolate chip cookie recipe I made at Gloria's house years ago.