Shirley Erskine, 82, has become famous for the sugar-laden treat which Andy and brother Jamie admit to gorging on during tournaments.
The world number two’s family and friends celebrated his first Wimbledon win in 2013 by tucking into the sweet snack in the stands of Centre Court.
And it was even dished out to guests at his wedding to wife Kim and to the stars of Strictly Come Dancing when Mrs Erskine’s daughter Judy Murray was a contestant on the show.
But now the pensioner has disclosed her recipe during a visit to school pupils in the Murrays’ home town of Dunblane.
She went to Dunblane Primary School to show primary six pupils how to make the shortbread as part of a cooking project.
And she agreed to allow the school to publish the recipe on their website.
Titled ‘Shirley Erskine’s Famous Shortbread’ it says the essential ingredients needed are 8oz of soft butter, 2oz of margarine and 2oz of vegetable fat all cut into chunks.
Those should be placed into a ‘warm’ bowl and mixed with 6oz of caster sugar, 4oz of corn flour, 2oz of self-raising flour and 8oz of plain flour.
Mrs Erskine then recommends splitting the mixture between three round 8 inch sandwich tins before putting it in a fan assisted oven at 120 degrees for roughly one hour until it is light brown.
Each tin should then be cut into 12 pieces while still warm and sprinkled with caster sugar before serving.
Following her visit to the school, Jamie Murray joked that she had probably left out a secret ingredient to throw people off the scent.
He tweeted: “Beware @DunblanePrimary Gran always leaves out the secret ingredient,” before Judy Murray replied: “Watch out Mary Berry.”
Earlier this year, doubles player Jamie revealed his gran had been enlisted to supply shortbread for the Great Britain Davis Cup team.
He said: “My gran’s shortbread is legendary. She’s been baking it for as long as I can remember.
“She doesn’t use a timer - she just knows when to take it out by her sense of smell.
“She always used to bring it to our tennis competitions and it has become a big part of our Davis Cup team preparations in recent years. Everyone loves it.”
Mrs Erskine said: “It’s become one of those silly traditions that I always supply some shortbread for the team.
“I bake some for every tie, though of course it’s not the sort of thing that players should have in their diet.
“I always find a way of getting the shortbread to the team, whether or not Roy [her husband] and I are travelling to the tie.”