ET's Katie Krause caught up with the No Doubt frontwoman at 102.7 KIIS FM's Wango Tango in Carson, California, on Saturday, where Stefani was as giddy (and surprised!) as ever about making beautiful music with her boyfriend.
"Anytime I've ever collaborated with anyone, it's always my favorite," she admitted. "But to do something with him -- because he's so talented and comes from such a different world -- to make music together, it was just so shocking! So amazing to do it live and share it with everybody."
"We're not. We probably should!" Stefani laughed to ET, admitting she wasn't quite sure what the appearance would like like yet. "It was amazing doing that song live [on The Voice]. It's incredible to do."
Stefani also got candid about her newest album, This Is What the Truth Feels Like, which was well-received after dropping in March.
"I prayed for that, I promise you," the mom-of-three said of the incredible reception. "I just so badly wanted to make something good out of something bad. I had to. I knew that that was my duty."
Stefani was especially excited to perform at Wango Tango, as she finally feels good about songwriting again. "It's just so fun to have new music, especially when I have not written a good song that I love in such a long time," she told ET. "This record… it happened so fast. It's such a shock that I could get in that place. It was so what I needed to do, so now that it's done and sharing it with people, it just feels so incredible."