Idina Menzel

At her holiday concert for iHeartRadio on Thursday night, Idina Menzel claimed she was “schvitzing”—sweating profusely—but that didn’t seem to affect her mien or her commanding performance.

Menzel put on a intimate (read: crowded) show for fans last night at the iHeartRadio Theater in New York to celebrate the launch of her latest studio album, Holiday Wishes. What the venue may have lacked in standing room was definitely made up for with Menzel’s powerful vocals, which reverberated around the room, which leaves one to wonder how she manages to do this, and then run over to do her starring role on the Broadway show, If/Then.

“Merry Christmas, Happy Halloween,” Menzel said, trying to cover all the holiday denominations as she started the night. “Happy Thanksgiving; Happy Holidays, everyone.”

The concert opened with “Do You Hear What I Hear,” in homage to Whitney Houston, who she said inspired her to sing the song when she was growing up. Menzel vacillated from more head-bopping songs such as “Holly Jolly Christmas” and a scat version of “All I Want for Christmas,” to more poignant songs such as Joni Mitchell’s “River,” a sonorous version of “White Christmas,” and “December Prayer,” a song Menzel wrote herself.

If “Let It Go” was starting to make Menzel nauseous (a la Kate Winslet and “My Heart Will Go On”), she certainly didn’t show it, as she sang a flawless acoustic rendition of the seminal ice palace-building song with two backup singers. While a few encore cries yelped from some of the more ardent Frozen fans in the audience, Menzel responded coolly by closing the night off with a tranquil cover of “Silent Night.” The set was shorter than expected, but understandably so, since Menzel had another job to get to that same night (and practically every night of the week). Menzel’s rich vocals and festive sparring with the audience, though, left the audience wanting more.