Prepare the rough puff pastry. In a large bowl sift the flour and mix it with salt . Incorporate butter to the flour, using a pastry blender or a fork or a pastry processor, until crumbs are formed. Add the water and stir until the water is incorporated. Wrap it with cling film, and refrigerate for 20 minutes.
Turn the pastry on to a lightly floured work surface. Roll the dough in one direction only, until 3 times the width, to a rectangle of about 6 X 17 inches (15 cm X 45 cm). Fold the top third down to the center, then the bottom third up and over that. Turn it to the left or right and roll out again to three times the length. Fold as before, cover with cling film and chill for at least 20 minutes before rolling to use. I actually made this a day before and chilled the dough overnight.
Prepare the rhubarb filling. Cut rhubarb in 1/2 inch (about 1 cm) pieces and place it in a sauce pan. Add sugar, lemon zest and ginger and cook over medium heat stirring constantly, for about 10 minutes until rhubarb is soft.Add vanilla extract, stir well and transfer the rhubarb mixture into a bowl and set aside to chill.
Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.
Onto a lightly floured surface roll the dough into a rectangle of ¼ inch thickness. Place it on the prepared baking sheet. Bake for about 20-25 minutes until crisp and golden. Remove from oven and set aside to chill.
Prepare the ricotta filling. In a bowl whip the cream with a hand mixer. Add ricotta cheese, the sugar and vanilla and mix until combined. Refrigerate until ready to use.
Right before serving, add spoonfuls of ricotta filling and rhubarb filling over the baked puff pastry and with a knife create swirls to create a marbled effect. Serve and enjoy!