Whisk everything together, or use a blender, immersion blender or food processor.
Pour into a large sauce pan, and set over medium low heat. Stir occasionally. DO NOT BOIL, or the egg will scramble. Just warm it through.
Place all the halved chickens into a large pans, like a roasting pan, or large bowl. Pour the sauce right over all the chicken. Refrigerate several hours or overnight.
Cook chicken over charcoal or in the oven (350F) until almost falling off the bone., 1- 1.5 hours Use the left over marinade to baste the chicken several times. Slow, low temperature and longer timing makes it better.
I use the convection feature of my oven to promote even browning.
If you choose to barbecue, which is what residents in upstate NY call it, referred to as grilling in other parts of the country, make sure your grill can be moved up and down. Start higher up, away from the coals and move the rack down as the chicken cooks.
Fresh coleslaw & baked beans is the perfect accompaniment, along with a fresh white roll. Which is what you'll get at any NY barbecue.