Return seeds to boil with 2 cups water for another 3 minutes and discard the liquid. Return the seeds to boil one last time with the other 2 cups of water for 3 minutes. Strain and reserve the remaining liquid.
In a large bowl, mix the fine semolina, flour, toasted sesame seeds, toasted nigella seeds, anise seeds, ground anise, ground fennel, and strained hilbeh.
Once the yeast is activated, add it to the dry ingredients with the olive oil and reserved hilbeh water. Mix well and press down firmly into a half cookie sheet, making sure it's even on all sides.
Cut your cake into the desired shape. I did vertical lines and then diagonal lines to make diamond-shaped pieces. Cover and let it rise in a warm place for 1-2 hours or until fluffy.
Bake in a preheated oven at 400F for 35-45 minutes or until it gets some nice color on top. Pour about 4 cups of simple syrup on top while the cake is hot, and let it sit at room temperature until completely cool.