Gwen Stefani celebrates 15th anniversary of her 'milestone' album, 'The Sweet Escape'

It's hard to believe it's been 15 years since Gwen Stefani released her smash-hit album "The Sweet Escape."

If you forgot, the singer made sure to remind her fans of the significance of Dec. 1.

"Happy 15th birthday to my second solo album!!" she wrote on Instagram, and shared several key photos from the album's cover shoot.

She also reflected on the impact "The Sweet Escape" had, calling it "such a milestone in my career."

Stefani signed off by telling fans, "I hope it’s still satisfying ur sweet tooth all these years later."

"The Sweet Escape" debuted on Dec. 1, 2006 and is RIAA-certified Platinum after selling over 1.7 million copies in the U.S. It produced the hit songs "Wind It Up," "4 in the Morning" and the album's title track.