In a medium-sized saucepan add the cornstarch, sugar, and salt. In a separate bowl, beat the egg until paler in colour: a good couple of minutes. Add in the milk and whisk to combine. Pour liquid into saucepan.
Cook mixture over medium heat, whisking often, until bubbles form and mixture thickens. Remove from heat and stir in butter and vanilla. Allow to cool slightly on stove top, stirring occasionally to prevent film.
Pour pudding through a fine sieve. Divide the pudding into individual cups, only fill halfway. Refrigerate until ready to serve.
Crush up some samoa girl scout cookies and mix it into the granola. Add as much of the granola mix as you desire, and top with whipped cream and a samoa cookie.