BEST IDEA EVER.
Fire up the grill.
Make up your favorite cookie dough.
Put a lightly oiled cast iron skillet on the grill to heat up for a few minutes, then pat down the dough. It'll be patchy at first, but as it heats up the top will smooth out a bit. Cover the grill and let it go. It's generally done when the sides are a deep golden brown. The texture is a bit like a cookie bar with a thick bottom crust.
So far we've made your general chocolate chip cookie and a peanut butter banana chocolate chip cookie. Both, obviously, were incredible.