Ava Phillippe Wishes Sweet Happy Birthday to 'Best Friend' Mom Reese Witherspoon

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Ain’t no best friend like your mom!

Ava Phillippe took to Instagram on Wednesday to mark her famous mom Reese Witherspoon’s 41st birthday.

WATCH: Reese Witherspoon Dishes on What It’s Like to Make a Movie With Oprah Winfrey

“Happy birthday to one of my best friends. ??❤️?,” the 17 year old captioned a pic of her mom with an incredible, rose-adorned, flaming birthday cake.

The teen, whose father is actor Ryan Phillippe, is a doppleganger of her Legally Blonde icon mom, as seen in another pic she posted over the weekend at fast-food chain In-N-Out.

Witherspoon recently opened up about her relationship with Ava now that she’s a teen and the “goofy” way she keeps in touch with her kids.

WATCH: Reese Witherspoon Talks Son Tennessee’s ‘Preschool Problems’

“Once you start to have teenagers, they become more adults, and you have these relationships that emerge with them,” the mom-of-three told Conan. “I communicate with them in funny ways. My daughter said the other day, 'It's like, we look like dad, but we got our weirdness from you.' What!? But I'm goofy. I send them weird Snapchats of me doing old man voices and goofy teeth -- that's the way we communicate.”

See more from the interview below.