As part of her "darling" son’s birthday celebrations the Chicago actress, 50, presented him with the stunning cake which was covered in strawberries and other fresh fruit.
Catherine posted a photo to her Instagram stories of Dylan holding the cake in front of giant balloons, spelling out his age. She simply captioned the snap "The Cake!!!!!"
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Dylan looked thrilled with his dessert and was smiling from ear to ear in the happy photo.
Catherine also took to Instagram to wish him a happy birthday and posted an adorable, black-and-white throwback photo.
She wrote: "Happy Birthday to my darling son Dylan. 20 years ago today I was granted the ultimate gift that keeps on giving. You are the light of my life and I love you with every ounce of my being."
Catherine and her husband Michael, 75, are also proud parents to their 17-year-old daughter, Carys, who dedicated a social media post to her brother for his birthday.
Dylan was spoiled by his mum on his birthday
The teenager shared a sweet photo of her hugging him and gushed: "20 YEARS OLD…. the most incredible brother and best friend I could ask for. I thank you for everything and love you more than you will ever know. I am the luckiest sister!"
The close-knit family have been on lockdown together due to the COVID-19 quarantine, and Catherine revealed in an Instagram Q&A what they had been up to.
Catherine shared the old photo from Dylan's childhood
She said: "Playing cards, playing Monopoly, having three meals a day, we haven't killed each other, we've respected each other's space."
When asked about the positives of lockdown, Catherine added: "Just to have the time to be together and to talk, it's been really great. I've really enjoyed having the whole family together."
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