In a large bowl combine the flour, sugar and salt. In a separate bowl whisk together the egg yolk, vanilla paste and water. Then slowly pour the egg mixture into the flour mixture, mixing until combined.
Using the stand mixer, gradually cut the butter into the dough mixture, beating on medium speed until small clumps have formed. Then transfer to a floured bench and knead the dough into a ball, before flattening into a round disk and wrapping in plastic wrap. Refrigerate for one hour. Preheat the oven to 160°C once the dough has chilled.
Roll out the dough between two sheets of plastic wrap into a circle approximately ⅛ inch thick. Then transfer to a mini tart pans with removable bottoms. Trim the edges of the dough in line with the edge of the tart pan and place a layer of aluminium foil over the top. Place pie weights over the foil and bake for in the oven for 25 minutes or until light golden brown.
Place a medium sized saucepan over medium heat, heat the cream and milk until the mixture boils. Remove from the heat and add the chocolate. Stir the mixture until the chocolate has melted and mixture smooth.
In a medium size bow whisk the eggs together. Slowly pour ¼ of the chocolate mixture into the eggs vigorously (to prevent from scrambling) until combined. Then gradually pour the mixture back into the pan, whisking to combine. Pour the filling into the tart and place in the oven for 25-30 minutes or until set. Then set aside to cool for 15 minutes.
Heat the sugar in a small saucepan over medium heat. Be careful not to burn the sugar by stirring continuously until the sugar has melted. Add the butter and whilst it bubbles continue to stir for 1-2 minutes or until the butter has melted. Then add the cream slowly to the mixture and allow to boil for 1 minute before removing from the heat.
Allow the caramel to cool for 15 minutes before pouring over the chocolate filling. Then refrigerate the tart for 2 hours to allow the caramel to set. Garnish with shaved chocolate (optional) and serve with ice cream or cream as desired.