Preheat your oven to 350°F (175°C) and brush a 9x13-inch baking dish with a portion of the melted butter to prevent sticking.

Working with two sheets at a time, gently scrunch the phyllo into accordion-like folds and nestle them into the dish. Continue until the entire dish is tightly filled with crinkled dough. Keep the unused phyllo covered with a slightly damp cloth to avoid drying out.

Place the prepared dish in the oven and bake for 10 minutes to help set the shape and start crisping the phyllo.

Remove from the oven and pour the remaining melted butter evenly across the surface. Return to the oven and continue baking for 12 minutes, or until the phyllo becomes lightly golden and crisp.

Meanwhile, prepare the custard by whisking together the eggs, milk, 1 cup of the sugar, vanilla extract, and cardamom until smooth and homogenous.

After the phyllo finishes its second bake, take the dish out and evenly pour the custard mixture over the warm pastry. Place the dish back into the oven and bake for an additional 40 minutes, or until the custard is set and the top is golden brown.

While the dessert bakes, make the syrup by combining the remaining 1 cup sugar and the water in a small saucepan over medium heat. Bring to a boil, then reduce to a gentle simmer for around 10 minutes until slightly thickened. Stir in the rose water and allow the syrup to cool to room temperature.

Once the cake is finished baking, remove from the oven and immediately drizzle the cooled rosewater syrup across the top, allowing it to fully absorb.

Sprinkle the crushed pistachios over the surface just before serving.