Preheat oven to 400 degrees F.
In a large saucepan over medium heat, add the water and sugar and cook to caramelize the sugar, about 10 minutes. Add the butter and stir until melted.
Take 4 large ramekins and pour caramel into bottoms and arrange 1 apple half, cut side down in the bottom of each ramekin. Take the remaining halves and cut them into 3 wedges so you can fill the gaps in the top of each ramekin to create a level surface on which the pastry will lie across. Sprinkle apples with some sugar. Roll the pastry out use a cookie-cutter to cut out circles the size of the ramekins and place over the apples folding it in at the edges. Make 3 or 4 holes with a knife and 1 in the middle to let steam out when baking. Bake for 20 minutes and then let it rest for 15 minutes. It is important that you do this otherwise the apples will fall apart when you turn it over. Take a dinner plate and put it over each ramekin. Turn it over and slowly remove the ramekin.
Serve lukewarm with store bought vanilla bean ice cream.