Both Princess Eugenie and her sister Princess Beatrice have kept their children out of the royal spotlight, but on Tuesday, October 15, Eugenie released a rare photo of her youngest son Ernesto in honor of his mother Sarah Ferguson, Duchess of York's milestone birthday.

“Happy birthday to my beautiful mama,” she wrote in an Instagram tribute, which included a carousel of unpublished family photos to celebrate Ferguson's 65th birthday. The post included two snaps of Ernesto in a casual green sweatshirt and jeans, spending time with his grandmother in a manicured garden.

The adorable toddler, who celebrated her first birthday in May, is Eugenie's second child with husband Jack Brooksbank, following older brother August, who turned 4 in February.

“I am so proud that you are a granny, a mommy, and a woman,” the princess continued in her post, adding, “You are an inspiration and our endless chats bring me so much happiness and incredible support. Sarah Ferguson 15."

Princess Eugenie posted several snapshots of her mother, including one in an elegant green evening gown, along with a sweet photo of Ernesto. In a casual portrait, the Duchess stands in front of the door of her hotel room.

The stylish mom of two, who went out last week carrying an unusual studded Chanel flap bag, also shared a photo of herself posing with her mother and Princess Beatrice.

This is not the first new photo Princess Eugenie has shared in the past week; on October 12, she posted an undated black-and-white wedding photo of her dancing with husband Jack Brooksbank in honor of their sixth wedding anniversary.

She also shared some family snaps to celebrate the news of Princess Beatrice's pregnancy on October 1, as did the Duchess of York, both of whom gave fans a rare glimpse of Beatrice's 3-year-old daughter, Sienna.