Cut the butter into pieces. It is important that these pieces are all the same size so that the butter melts evenly and does not burn.
Melt the butter over low heat. Pour into a container.
Wait about 10 minutes. Using a large spoon, remove all whey, i.e. the foam that forms on top.
Roast pistachios in a small dry skillet on low heat for about 10 minutes. Chop only after roasting.
Preheat oven to 350F/180C.
Line a baking pan or casserole dish with parchment paper.
Line countertop with parchment paper.
Take a sheet of filo and brush slightly half of the area with butter, without pressing with the brush. Fold the sheet in half to form a rectangle.
Mix nuts and cinnamon. Lightly sprinkle the dough with this mixture.
Place the wooden stick at the bottom of the filo sheet (narrow side) and wrap loosely in order to obtain a roll of dough around the stick.
Wrinkle the dough starting from the end and tightening toward the middle.
Remove the stick. The roll of dough should be wrinkled. Using a sharp knife, cut the two to get a couple of cakes. Place each cake in pan and cover with fabric to prevent the dough from drying out. Also cover the filo sheets that are waiting so they do not dry out. Repeat the process with the remaining 7 sheets.
Bake for 20 minutes until the cakes are golden. Prepare the sugar syrup while the cakes are in the oven. Put the water and sugar in a saucepan. Bring to a boil until the syrup begins to thicken.
Remove from heat. While stirring, pour the lemon juice and orange blossom water. Immediately put back on the fire and bring back to a boil, stirring constantly. Remove the pan from the heat. Let cool a bit. Pour syrup generously over the cakes as they come right out of the oven.