1. Start by making your syrup so that it has time to cool. Add all of the ingredients to a small saucepan. Bring it to a boil and then immediately reduce it to a steady simmer. Cook for 15-20 minutes, or until reduced in volume and thick enough to coat the back of a spoon. Remove from the heat and set aside to cool. Remove the cinnamon stick and cloves if used.
2. Meanwhile, make the filling. Pulse the pistachios and walnuts in a food processor until crumbs are formed.
3. Add the cinnamon, lemon zest, and orange zest, ground cloves, and salt if using. Stir, then add the maple syrup and stir again to combine everything.
4. Preheat the oven to 180 degrees. Lightly grease an 8-by-8-inch baking dish, or similar sized dish.
5. Gently unroll the dough, and trim it to the size needed to fit your pan. Get a damp kitchen towel and use it to cover the dough to keep it moist.
6. Add approximately 3 sheets of dough at a time to your pan. Brush with a very light coating of olive oil and continue. Do this until you have used about 1/3 of the sheets.
7. Sprinkle 1/2 of the spiced nut filling onto the dough. Gently spread it out into an even layer as best you can without tearing the dough too much.
8. Continue layering and oiling sheets of dough until you have used approximately 2/3 of the sheets. Add the remaining half of the filling at this point, and finally, continue with the remainder of the dough. After lightly brushing the top layer of dough with oil, use a sharp knife to cut the baklava into pieces of your choosing. Be sure to cut all the way through to the bottom of the pan.
9. Bake uncovered for approximately 25-28 minutes, or until nicely browned on top. Immediately after removing the baked vegan baklava from the oven, pour the syrup evenly over it. Try to get some of it it in all of the different cuts so that it can soak through to the bottom.
10. Let cool to room temperature before slicing and serving. Leftovers can keep in an airtight container in the refrigerator for a few days, or frozen.
