The new series is expected to be the first to air on the show's new home and Channel 4 are going all out for celebs.
The All Stars special will be in aid of Stand Up To Cancer charity and is set to be broadcast in the autumn.
“After they managed to wrestle the Great British Bake Off away from the BBC, the bosses know the pressure is on," a source spilled this weekend.
They told The Sun newspaper: “They’ve made signing up names for the celebrity special priority and Michelle Keegan is top of the list, as she is apparently a very keen baker.
“She is also a real Bake Off fan and thinks it would be a fun thing to do. The issue is whether or not she can fit it in with her other work projects."
As well as the celebrity spin-off, it was confirmed earlier this year that a full series of GBBO will air in 2017.
In 2016 news broke that Channel 4 had purchased the rights to the hit baking show in a multi-million pound, three-year deal.
However as part of the BBC's original contract, it had the power to enforce a one year wait before any other channel could air the show.
But the BBC has waived this clause allowing the series to begin on Channel 4 later this year.
An insider told the BBC News: "We don't want to get in the way of them reinventing the programme."
As well as changing channels, judge Mary Berry and hosts Mel Giedroyc and Sue Perkins will be leaving the Great British Bake Off on Channel 4.