Preheat oven to 180°C, fan forced.
Add all pastry ingredients to mixer bowl and combine for 5 sec/speed 6/MC on. Scrape out and wrap up in glad wrap. Put it in the freezer while you prep the remaining ingredients.
Combine water, sugar and vanilla bean. Coat your apples in mixture then pour everything, including butter, (but not the pastry!) into a 20 cm baking dish. Bake in the oven for 20-25 minutes until apples are soft and golden. You want your liquid to reduce right down to no more than 5 Tbsp. At this point you can carefully arrange your apples in a pretty way if desired.
Take your prepared pastry and roll it out to a rough circle shape. Press it in to the baking dish, on top of the apple mixture. Bake until golden brown, about 15 minutes. Because this is almond meal based pastry, this time may vary. When golden brown, turn out on to a plate and serve after resting for 5 minutes.