The singer, who happens to be the most flat-chested member of the group, tells Radio 1 that she has been eating the cookies so that by the time the Spice Girls' reunion world tour kick starts soon, she will be seen with bigger breasts.
"I'll be a guinea-pig for them, can you imagine if my boobs got bigger suddenly? That'd be so great!" The Sun quoted her, as saying.
The biscuits, with a calorific value of 68.7 each, contain trans-fats, which are sent directly to the breast area.
They also contain 50mg of "breast-enhancing herb" Pueraria Mirifica.
Manufacturers claim that eating two cookies a day will help women enhance their twin assets by at least a cup-size.
In the meantime, Posh has reportedly put all the other band members on a strict diet and exercise regime to make sure that they get in shape for the tour.
A source said: "Victoria has told the girls her secret to getting in shape is 200 sit-ups a day and a diet of edamame soya beans, strawberries and lettuce.
"She is determined to make sure the reunion goes well because her image is important to her.
"She wants the girls to all look their very best, and says her diet is a guaranteed way of losing the pounds."
The comeback tour kicks off in Vancouver, Canada, on December 2.