Upon receiving the command from Mairon, Ungoliant scuttled off to a nearby tree. It wasn't as lush as the trees which grew around Ered Gorgoroth, but it would do. With her she brought the cart of food and munched on them to prepare herself for the laying. Egg-laying was easy enough to do with just a few tasty horse meat, though they would not be fertilized. But she trusted Mairon would find a method. The light of the Two Trees has since been spewed out of her, transformed in her body into a thick smoke which became the life-giver of her precious children, from which Shelob herself (her favorite among her children) was born.
It was not easy spawning children without a mate, but she made do with what she had. If she could turn the energy into her stomach, she could spawn. Otherwise, she could lay hundreds of eggs at once.
As she munched happily at her meal she glanced up at Ancalagon with lust. He may not become the father of this batch of eggs, but the sight of him alone was needed. She shook her rear with a slight fever, and out spewed her eggs.
She stood still till she was done, then turning around she admired her creation for a moment before wrapping them in silk, weaving them into a sac.
"Where are you, Mairon?" she called out, clutching the bag of eggs close to her as she scuttled out from her nest by the tree.