Prepare the syrup by combining sugar, water, lemon juice, corn syrup (optional), cinnamon sticks (optional), and cloves (optional) in a saucepan.

Stir over low heat until sugar dissolves.

Increase heat to medium and cook until slightly syrupy (225°F on a candy thermometer), about 5 minutes.

Remove from heat and discard cinnamon sticks and cloves.

Let the syrup cool completely.

Combine chopped nuts, sugar, cinnamon, and cloves or cardamom (optional) for the filling.

Preheat the oven to 350°F (175°C).

Grease a 12x9 or 13x9 inch baking pan.

Place a sheet of phyllo dough in the pan and brush with melted butter.

Repeat with 7 more sheets, brushing each with butter.

Spread half of the nut filling evenly over the phyllo.

Top with 8 more sheets of phyllo, brushing each with butter.

Use any torn sheets in the middle layer.

Spread the remaining nut mixture over the phyllo.

Top with a final layer of 8 sheets of phyllo, brushing each with butter.

Trim any overhanging edges of the phyllo.

Using a sharp knife, cut 6 equal lengthwise strips through the top layer of pastry.

Make 1 1/2-inch wide diagonal cuts across the strips to form diamond shapes.

Lightly sprinkle the top of the pastry with cold water.

Bake for 20 minutes at 350°F (175°C).

Reduce heat to 300°F (150°C) and bake until golden brown, about 15 more minutes.

Cut through the scored lines to separate the baklava pieces.

Slowly drizzle the cooled syrup over the hot baklava.

Let cool completely for at least 4 hours before serving.