Blend or crush digestive biscuits into a fine crumbs. Pour into a bowl, add in melted butter and mix well. Pour into a 24 cm removable bottom pie pan. Press evenly to the bottom and the side of the pan. Chill in the fridge for 30 minutes.
In a bowl, add in condensed milk, lime zest, lime juice and whisk to combine.
Pour into the previously chilled base. Spread evenly and chill in the fridge overnight.
In another bowl, add in whipping cream, icing sugar, vanilla extract and whisk until stiff peaks. Pipe on chilled pie. Decorate with some slices of lime.