That is a good question.  I am sure it would work however you will have to do a little experimenting.  I would suggest leaving the water out of the brownie recipe and then adding a little additional flour, so the dough is the consistency of a drop cookie. Start with maybe 1/4 cup.   Once mixed make little balls and roll them in powdered sugar.  Try baking a few and see how they turn out.  If they spread out really thin when baked add a little more flour and if too thick add a little water.  You can also add some chocolate chips and vanilla to the dough if you want a more chocolate flavored cookie.  

Good luck and thanks for using Ask Extension

Nellie Oehler