For a slightly cake-like cookie with a gooey center, Food52 recommends cooking the giant slab of dough for around 1 to 1.5 hours on high or 3.5 to 4 hours on low. If you prefer a firmer or crispier cookie, cook it another 15-30 minutes on high until its edges get nice and golden, and you may need to play around with the timing depending on what size your crockpot is.