Prepare the simple syrup first and let it cool.
Preheat oven to 350 F.
Process the pistachios and powdered sugar in a processor. Transfer to a bowl and set aside. You will split the amount into 2 portions, leaving some fir garnishing
Unfold the phyllo sheets and smooth out to flatten. Cover with a damp towel, not wet, to prevent it from drying.
Brush the base of a 9 x 14 inch pan with some ghee. Place one sheet of phyllo and brush again with ghee. Repeat to get a total of 15 sheets, brushing ghee in between each sheet. Add in half of the ground pistachio and spread evenly.
Add in one sheet over the nuts and brush by dabbing only because it will move if you brush it normally. Add 9 more sheets, total 10 sheets, brushing in between each sheet. Press press down the surface very well with your palm to compress the nuts.
Add the other half of the ground pistachio and top with 15 more sheets the same way you did the first layer. Before brushing the top with ghee for the last time, press down the surface really well again with your palm to compress the layers.
Using a sharp knife with a pointed tip, cut the baklava into diamond shapes. Refer to my blog photos for step-by-step photo reference.
Place the tray on the middle rack of your oven and bake for 40 minutes. At this point the edges and baklava should be lightly brown in color and you can turn on the top broiler for just 1-2 minutes watching it "very closely" until you get the golden color you prefer. Do not take your eyes off of it or else they will burn super fast.
Remove from the oven and drizzle 1-1¼ cup of simple syrup evenly all over the baklava. Use more or less to preference. I like using a squeezable bottle to spread the syrup evenly on the baklava.
Garnish with crushed pistachio, allow to cool and enjoy.