The unusual post led many fans to believe the outspoken mum was hinting at a gender reveal for the younger Princess of York.
"Lovely! Am wondering if there's a hidden message in your post... 🤔," one fan questioned.
The comment certainly could be true - many baby celebration cakes are a gender neutral colour like yellow.
And the addition of the pink flower certainly has some thinking it could be a girl!
Fans have been preoccupied with the prospect of another royal baby for months, with many sending newly married Eugenie love and questions on social media asking is an announcement could be on the cards for her and Jack.
"Can't wait until we get a Royal Baby Brooksbank - you're my favourite royal couple!" one person wrote on the Princess' latest photo.
In the UK, fans are so sure that Prince Andrew's daughter is pregnant that British bookmakers have slashed the odds on Eugenie and Jack confirming that they are expecting a baby.
Odds are now at 1/4 with bookies expecting an announcement any day now.
“It looks like the Royals are getting broody,” Alex Apati of Ladbrokes told The Sun.