Line your baking dish with parchment paper.

In a medium saucepan, combine the granulated sugar and 1/2 cup of water. Heat over medium heat, stirring until the sugar dissolves.

In a separate bowl, whisk together the cornstarch and 2 cups of water.

Slowly pour the cornstarch mixture into the saucepan with the sugar syrup. Stir continuously to avoid lumps and cook on low heat.

Once the mixture thickens, add the lemon juice and rosewater.

Add the chopped nuts to the mixture and stir well.

Pour the lokum mixture into the prepared baking dish and smooth the top with a spatula.

Allow the lokum to cool at room temperature for at least 4 hours or until fully set.