Lauren Conrad is celebrating her son's first birthday. The 32-year-old former "The Hills" and "Laguna Beach" star marked the milestone by throwing a party for Liam, her son with husband William Tell, on Saturday. Conrad shared a photo on Instagram of Liam digging into his birthday cake. Decorative streamers and a banner reading "Happy Birthday Liam" can be seen in the snapshot. "Celebrated our sweet Liam's birthday today," Conrad captioned the post. RELATED LINK: 'DANCING WITH THE STARS' PROS AND THEIR SIGNIFICANT OTHERS: WHO'S DATING OR MARRIED TO WHOM!? (PHOTOS) Conrad dedicated a sweet post to Liam on his official birthday Thursday, July 5. "Celebrating 1 year with our little guy," she wrote. "Happy Birthday Liam!!" Conrad said in an interview with People in September that Liam is growing up quickly. "I think that you can become a little overwhelmed, just being at home with your baby all day," the star said. "But seeing how fast they chance, you realize it's so important not to miss anything." RELATED LINK: 'THE BACHELOR' FRANCHISE COUPLES NOW: WHO IS STILL TOGETHER?? (PHOTOS) "It's been great!" she added of motherhood. "Honestly, it's exactly as everyone describes it. It's the best and hardest thing you'll ever do."