Mix the two types of flour and salt in a bowl. Add the butter and rub together using your hands to form an even, crumbly mixture. Dissolve the yeast in water, add to the mixture and quickly combine to form a soft dough. Cover and leave to rest for approx. 10 mins. On a lightly floured surface, roll out the pastry into a circle (approx. 34 cm in diameter), place in the prepared tin, prick firmly and chill.
Toast the caraway seeds in a wide-bottomed frying pan, set aside. Heat the butter in the same pan. Sauté the onion and Swiss chard in batches over a medium heat for approx. 12 mins., stirring occasionally. Stir in the caraway seeds and season. Leave the vegetables to cool, drain. To make the sauce, mix the cream with all the other ingredients up to and including the pepper.
Spread half of the vegetable mixture over the pastry base. Sprinkle with half of the cheese cubes. Repeat the process and pour the sauce over the top.
Bake for approx. 30 mins. in the lower half of an oven preheated to 200°C.