Princess Eugenie’s son August Brooksbank celebrated his first Halloween on Sunday. The mom of one marked the spooky holiday with a photo of her baby boy in his adorable blue monster costume. “🎃 👻... wonder what they are talking about,” she captioned a picture of August playing on the floor with a stuffed Minions toy.

The Princess’ brother-in-law Edoardo Mapelli Mozzi reacted to the mons-terrific post with emojis, commenting: “🤣❤️.” Over on her Instagram Story, Eugenie also shared a picture of her “attempt at a scary” carved pumpkin as well as a picture of August crawling in his costume. On the picture of her little boy, she wrote, “At least my little Halloween monster is scary.”

Eugenie and her husband Jack Brooksbank, who celebrated their third wedding anniversary last month, welcomed their first child on Feb. 9. This Halloween was also a first for August’s newborn cousin Sienna Elizabeth Mapelli Mozzi. Princess Beatrice and Edo’s daughter was born on Sept. 18.

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Sarah Ferguson has called both of her daughters “phenomenal mothers.” “They were great children but now they’re phenomenal mothers,” she previously told HOLA! USA’s sister brand HELLO!. “And now, I have these two exceptional grandchildren all in one year.”

“You know it’s pretty incredible, but everyone asks me, ‘How are your grandchildren?’ Sarah added. “Well, firstly, I look at my girls being wonderful mothers and then I see these incredible beings and it’s so funny because when August smiles at me now, because he’s seven and a half months, you actually know he genuinely likes you. It’s not a put-on smile, he genuinely finds me very funny which is quite lucky.”