Put one sheet of puff pastry on parchment paper. Roll out the pastry until it is large enough to accomodate a 10-12-inch diameter circle. With a pizza cutter, kitchen shear, or knife, cut the circle using a pizza tray, dish, or paper stencil to guide you. Save the scraps for decorating or for making smaller pastries. 

Move the parchment with the circle of pastry onto a quarter or half sheet pan and refrigerate it to keep the dough chilled. 

Roll out the chilled marzipan into a thin sheet, cutting it the same way you cut the puff pastry circle, but slightly smaller in diameter. Do not be concerned if the edges of the marzipan are imperfect - they do not show once the top layer of pastry is on. Remove the pastry circle from the refrigerator and place the marzipan on top of the pastry. There should be a border of pastry approximately 1/2 - 1-inch. 

Spread the finely chopped or grated chocolate on top of the marzipan. Refrigerate the pastry and marzipan while you form the second circle. Hint- I used grated, but finely chopped would be easier keep in place. Using the egg yolk and water mixture, baste the edge of the pastry (the part not covered by marzipan and chocolate.) Again, no need to aim for visual perfection. Even if the chocolate gets onto the edge, the tarte will still look good and taste delicious.  

Preheat the oven to 375 degrees. 

Roll out the second sheet of puff pastry the same way you did the first. Take the pastry circle with the marzipan and chocolate out of the refrigerator. Using the egg and water mixture, baste the circle with the marzipan and chocolate. Gently place the second pastry circle on top of the chocolate and lightly press down on the edge to seal the two pastry circles together. Do not worry if the edges are not completely sealed. 

Put a small cup or other circular object about 1-inch in diameter in the middle of the circle. Press it gently into the pastry, enough to make an indentation, but not hard enough to cut all the way through to the bottom of the pastry circle underneath. From the small cup, cut a line to the edge of the pastry at the top of the circle. Do the same at the bottom and on the sides so that you have four equal sections. Now cut each section in thirds, so that you have a total of 24 strands. 

Turn each strand three times (in the same direction), so that you create twisted rays around the cup/sun. Then use the egg yolk and water mixture to glaze the outside of the pastry and sprinkle on some or all of the chocolate that has spilled out as you twisted the strands. (You may have to gently lift up some of the strands to catch chocolate that fell underneath.) 

If you have leftover dough and filling you can make mini versions of the tarte soleil and/or fold a circle with filling over to create a half moon hand pie. 

Bake for about 30 minutes, until the top starts to brown. Let the tarte soleil cool for 10-15 minutes, until cool to the touch.