He eagerly accepts the cookie, and, well... snarfs it down.

He practically has to juggle with it given his lack of limbs, but eventually the cookie is no more. This is... delicious. Not for the simple fact that it's delicious, but the fact that it tastes like nothing in the underground at all. As if he tried everything and everything that could be eaten and this is the first time he's experienced a new thing.

This feels like a feeling-- what is it...? That means this place is full of a lot of new sensations... not trapped beneath the Earth, making due with what they got. He feels a revelation.

"It's...! It's. Not bad." Flowey was still mostly negative, after all. "I guess I can rate it a five."