Kate Middleton has an adorable way of celebrating her children's birthdays.

On Monday night's BBC special "A Berry Royal Christmas," Middleton, 37, revealed to celebrity baker Mary Berry that she usually stays up late to make a cake before each child's special day.

“It’s become a bit of a tradition that I stay up until midnight with ridiculous amounts of cake mix and icing and I make far too much," said the Duchess of Cambridge (via Us Weekly). "But I love it.”

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Kate and her husband, Prince William, share three children: Prince George, 6; Princess Charlotte, 4; and Prince Louis, 19 months.

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In the special, Kate and Prince William were joined by Berry, 84, to prepare food as a thank you to those that volunteered with their charity organizations over the course of the year.

Middleton also revealed that Berry was the inspiration for one of Louis' first words.

Kate Middleton and Prince William pose for a photo with their three children, George (right), Charlotte (middle) and Louis. (AP)

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"One of Louis' first words was Mary, because right at his height are all my cooking books in the kitchen bookshelf. And children are really fascinated by faces, and your faces are all over your cooking books and he would say 'That's Mary Berry,'" Kate told BBC. "He would definitely recognize you if he saw you today."