〜と (manner): in a … way (after sound and mimetic words)

After a sound or mimetic word (きらきら, ゆっくり, ぱっ) or a 〜々 word (次々, 堂々), と turns it into an adverb: how something happens.

Many of these words can drop と (ゆっくり歩く = ゆっくりと歩く). With する they describe a state: 堂々とした態度 "a dignified attitude", 外がカリッとしている "crispy outside". This と is neither "and" nor a quotation.