。
She didn't even crack a smile when she saw me.
Literal
She [topic-は] me [object-を] saw [and-て], briefly-smile [even-さえ] didn't-do.
にこり is one of Japanese's many smile mimetics — specifically a brief, warm flash of a smile, often paired with する or とする to mean 'to smile (a little).' Other smile mimetics carve out fine distinctions: にっこり (broader warm smile), にやり (smug/mischievous), にたり (knowing/sinister), にんまり (deeply satisfied) — a precision English lacks. The negative pattern にこりと(さえ)しない ('didn't even crack a smile') is a vivid way to express coldness or refusal to acknowledge. The さえ adds emphasis: not even the smallest smile.