2) In a medium bowl, combine digestive biscuit crumbs and brown sugar. Stir in melted butter. Press the mixture firmly into bottom and up sides of a 25cm spring form pan. Bake for 8 minutes and let the crust cool completely before spreading the pie filling over it.
3) In a large bowl, with an electric mixer at medium speed, beat cream until slightly thickened. Gradually add the sugar, beating until soft peaks form. Add condensed milk and beat until stiff peaks form. Beat in lime juice, lime zest, and single cream. Once the mixture as reached desired flavor and consistency, gently spread pie filling over cooled crust. Cover and freeze for 4 to 6 hours or until firm. Cut into wedges and garnish with fresh lime slices, serve cold.