Mix the flour, salt, onions and yeast in a bowl. Add the butter and water and knead to form a soft dough. Cover and leave to rise for approx. 1 hr. until doubled in size.
Cook the Brussels sprouts in salted water for approx. 10 mins. until almost soft, drain and cut in half. Heat the clarified butter in a non-stick frying pan. Brown the chicken all over for approx. 2 mins., remove and allow to cool slightly. Combine the mustard, honey, salt and pepper. Coat the chicken in the mixture. Combine the quark and Mascarpone, season.
Roll out the dough on a lightly floured surface (approx. 30 x 50 cm). Cut a 5 cm strip from one of the narrow edges for decoration, cover with a damp cloth. Divide the remaining dough into quarters. Place the ham in the centre of the pieces of dough. Spread half of the quark mixture on top. Place 2 chicken halves on each. Arrange the sprouts on top and spoon over the remaining quark. Brush the edges of the dough with a little water. Fold the two shorter edges over the filling and press down. Press firmly on the two side openings, folding under if necessary. Cut the reserved pastry dough into strips and use these to decorate the parcels, then place on a tray lined with baking paper. Brush the chicken parcels with egg.
Approx. 20 mins. in the centre of an oven preheated to 200°C.