Preheat oven to 350 degrees. Butter the bottoms and sides of a 9×13 inch pan.
Toss crushed nuts with cinnamon and cardamom. Set aside. Unroll phyllo dough. Cut whole stack in half to fit pan. Cover phyllo with a dampened cloth to keep from drying out as you work. Place two sheets of dough in pan, butter thoroughly. Repeat untill you have 8 sheets of phyllo layered. Sprinkle with 2-3 tablespoons of nut mixture on top. Top with two sheets of dough, butter, nuts, layering as you go. Top layer should be 6-8 sheets deep.
Using a sharp knife cut into diamond or square shapes all the way to the bottom of the pan. Bake for about 50 minutes until golden and crisp.
While baklava is baking boil sugar and water until sugar is melted. Add cardamom and lemon juice. Simmer for about 20 minutes.
Remove baklava from oven and immediately spoon sauce over it. Sprinkle ground pistachio nuts on top. Let cool. Leave uncovered as it gets soggy if it is wrapped.