Start making the dough by mixing together the rice flour, buckwheat flour, xantham gum, baking powder and a pinch of salt.
Working with your hands, add the butter to the flour mix and rub with your fingertips until the mixture looks like fine breadcrumbs. Add 2 to 3 tablespoons of cold water and mix the dough until soft. Roll into a ball and set aside.
Pre-heat the oven to 180C/350F/Gas 4.
Heat some olive oil in a large frying pan. Add finely chopped onion and crushed garlic and cook until soft.
Add the finely chopped leeks and quartered broccoli florets. Cook for around 15mins until soft. Season to taste.
In a separate bowl mix together the eggs, milk, cream, curry, grated cheese and some grated nutmeg. Season to taste.
Roll out the pastry and place in a Ø 28cm / 11 inches loose bottomed tart tin. Do not worry if it breaks, just patch it up in the tin.
Transfer the cooked vegetables followed by the egg mixture on top of the pastry. Make sure you spread the egg mixture evenly.