Step 1

Simmer 1 3/4 cups sugar and orange juice in saucepan over medium heat, stirring to dissolve sugar. Boil over medium heat until reduced to 1 1/2 cups, about 8 minutes. Add cardamom. Cool syrup.

Step 2

Place nuts and 2 tablespoons sugar in processor. Using on/off turns, process until most of nuts are finely ground (the largest pieces should be the size of small peas). Mix nuts, 6 tablespoons sugar, and cinnamon in medium bowl.

Step 3

Preheat oven to 350°F. Brush 13x9x2-inch glass baking dish with some of melted butter. Place 1 phyllo sheet on bottom of dish. Brush lightly with melted butter. Repeat 9 more times with phyllo and melted butter. Sprinkle half of pistachio mixture (about 1 1/2 cups) evenly over phyllo. Place 1 phyllo sheet over nuts; brush lightly with butter. Repeat 9 more times with phyllo sheets and melted butter. Sprinkle remaining pistachio mixture evenly over. Place 1 phyllo sheet atop nuts; brush with butter. Repeat 9 more times with phyllo sheets and melted butter.

Step 4

Using sharp knife, cut diagonally through top phyllo layer from top left corner to bottom right corner. Cut top layer of phyllo into 1-inch-wide rows parallel to both sides of first cut. Turn pan and cut rows about 2 1/4 inches wide, forming diamond pattern.

Step 5

Bake baklava until golden brown and crisp, 50 to 55 minutes. Drizzle syrup evenly over hot baklava. Cool in pan on rack. Recut baklava along lines all the way through layers. DO AHEAD Baklava can be made 2 days ahead. Store airtight at room temperature.

Step 6

Sift powdered sugar over, if desired.