The couple stepped out at Marquee in Las Vegas on Saturday, where they celebrated their upcoming nuptials in the Library Room with a large group of friends.
"Aaron rocked a bow tie, and Lauren donned a veil," an onlooker tells PEOPLE. "The lovebirds were dancing and canoodling."
The Breaking Bad star and Parsekian were also surprised with his-and-her cakes – the groom's cake was designed to look like steps on the Parisian street where Paul proposed. It included a special message, "My pretty bird, thank you for loving me."
Last October, Paul explained to PEOPLE just how he popped the question.
"It's just this little courtyard outside of this hotel, and we were just dancing to Édith Piaf by ourselves on New Year's and then I begged her to marry me," he said.
– Melody Chiu