Place cookies into plastic bag and smash until fine crumbles form, or use a food processor and make it as fine as possible.
In a large bowl, combine cookie crumbs and melted butter and mix until it clusters.
In a cupcake tin, put a spoonful of the crumb mixture and form into crusts.
Freeze for 2 hours.
In a medium saucepan, heat sugar and water until amber brown. Do not stir!
Take off the heat and pour in the heavy cream and vanilla, stirring until caramel forms. Caution: adding the cream will cause sugar to boil, so carefully mix.
Quickly pour caramel into the cookie crust and let it sit until caramel is firm. Approximately 5 minutes.
Heat up the heavy cream and add the dark chocolate. Let the chocolate sit for a minute and stir until smooth.
Pour a spoonful of chocolate over the caramel and then refrigerate for an hour or until the chocolate is firm.
Sprinkle the tarts with some sea salt to balance sweetness if desired.