Katharine McPhee Shares Photos from Son's Party, Calls Motherhood the 'Greatest Fricken Thing'

Katharine McPhee is expressing her love for motherhood as she celebrates her son's first birthday.

On Tuesday, the new mom, 37, shared a series of photos from son Rennie's first birthday party alongside a heartfelt message to her baby boy on Instagram. The singer and actress shares her only child with husband David Foster.

"Happy Birthday to our cutie baldie baby who turns 1 today! Where does the time go?" McPhee begins. "I know you've heard this before but being a mommy is the greatest fricken thing in the world. Here are some highlights from his 1st party. I LOVE YOU SO MUCH RENNIE!!!!"

For his safari-themed party, baby Rennie wore green khaki shorts with a matching jacket over a onesie with a dinosaur on it.

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The get-together, where Foster's 39-year-old daughter Erin was also pictured, featured a ball pit with a plush zebra, several play areas and extravagant balloon displays placed throughout the room.

On Sunday, the American Idol alum posted additional pictures from Rennie's party, including a snap of her son's birthday cake, which was decorated with blue and yellow frosting and toy safari animals walking on top.

Last year, McPhee opened up to PEOPLE about the realities of motherhood, sharing that "it takes a village" when raising a baby, so "everyone needs help."

"I bow down to these women who just do it completely on their own, but you know, you say it takes a village, and it does because babies need lots of attention," McPhee said.

"And I think it's healthy for babies to have multiple people around them who love them, friends, families, nannies," she continued. "I mean, whoever you can, just [to] help you out — and it also, in turn, helps the baby."