01 - Preheat oven to 350°F. Generously grease a 9x13-inch baking pan with melted butter.
02 - Combine walnuts, almonds, pistachios (if using), sugar, cinnamon, and cloves in a mixing bowl. Mix thoroughly to distribute spices evenly.
03 - Place one phyllo sheet in prepared pan. Brush lightly with melted butter. Repeat layering and buttering 6-8 sheets total for the bottom layer.
04 - Sprinkle one-third of the nut mixture evenly over the buttered phyllo sheets.
05 - Layer and butter 4-5 additional phyllo sheets. Add another one-third of the nut mixture.
06 - Repeat with 4-5 more buttered phyllo sheets, then the remaining one-third of the nut mixture.
07 - Layer remaining phyllo sheets, buttering each sheet including the top layer.
08 - Using a sharp knife, cut baklava into diamond or square shapes before baking.
09 - Bake for 35-40 minutes until phyllo turns golden brown and crisp.
10 - While baklava bakes, combine sugar, water, and lemon juice in a medium saucepan. Boil for 8-10 minutes. Remove from heat and stir in honey and rose water or orange blossom water if using.
11 - Pour hot syrup evenly over hot baklava immediately after removing from oven. Allow to cool completely at room temperature for syrup to fully absorb before serving.