1. Prepare the pizza dough according to the instructions.
2. Combine the potatoes with the olive oil, salt, pepper and rosemary.
3. Bake the potatoes in the oven at 200°C for about 30 minutes or until tender.
4. Roll out the dough into a circle on a floured surface.
5. Carefully move the dough onto a piece of baking parchment. Make 8 cuts in the dough all the way around, from the outer edge of the dough in towards the centre. Each cut should be about 6cm long and should not extend all the way to the centre.
6. Then, make 8 small cuts about 2cm long from the centre of the dough out towards the edge.
7. Spread tomato sauce over the part of the pizza base that has not been cut through. Arrange the potatoes, red onions, prosciutto and the Double Cream Brie in a circle on top of tomato sauce.
8. Starting from the outer edge of the dough, lift up each corner where you made the cuts. Fold the corners towards each other so they partly cover the filling and form a triangle. Then, lift up the corners of the dough along the cuts in the centre, folding each one up and out to cover the filling as well.
9. Preheat the oven to 250°C and put an empty roasting pan in the oven.
10. Carefully move the pizza on the baking parchment into the hot roasting pan.
11. Brush the pizza with egg yolk and bake in the middle of the oven at 225°C for about 20 min. or until crispy and golden.
12. Sprinkle with chopped fresh parsley and serve.