Prepare the Syrup:

In a medium saucepan, combine sugar and water. Stir until dissolved.

Bring the mixture to a boil, then reduce heat and simmer for 15 minutes.

Add lemon juice, stir, and let the syrup cool to room temperature.

Prepare the Baklava Layers:

Preheat your oven to 350°F (175°C).

Grease a 9x13-inch baking dish with melted butter.

Lay one sheet of phyllo dough in the dish and brush lightly with melted butter. Repeat for 20 layers.

Spread half of the ground pistachios evenly over the dough.

Build the Top Layers:

Layer another 20 sheets of phyllo dough, brushing each with butter as you go.

Cut the Baklava:

Using a sharp knife, cut the baklava into diamond or square shapes before baking.

Bake:

Place the tray in the preheated oven and bake for 45-50 minutes, or until golden and crisp.

Add Syrup:

Remove the baklava from the oven and immediately pour the cooled syrup evenly over the hot baklava. Allow it to soak in.

Serve:

Let the baklava cool completely, garnish with extra pistachios if desired, and serve!