Cream together the margarine, 1/2 sugar and 1/2 cup brown sugar until well mixed. Then add egg yokes, water and vanilla, mix throughly. Last add the flour and baking soda.
Spread the dough mixture into a 9x13" pan until even. Next spread 1 cup chocolate chips over the dough pressing them into it.
Next mix the 4 egg white till stiff peaks form, then adding 1 cup of brown sugar a little at a time.
Bake at 350 for 30 minutes, 22-25 for gooey bars.
Madagascar Vanilla (purchase at Chefs Catalog) Of all the vanilla's I've used this is my favorite. Once you've tried it you won't go back!