In a large, wide and heavy saucepan bring the milk to a boil over medium high heat. And let it boil for 2-3 minutes.
Add lemon juice to the milk, it will begin to curdle. Use minimum amount of lemon juice to just start the curdling process and prevent the whey (milky water) from completely separating immediately.
Boil for 5 minutes and remove approx. 1 ½ cups of the whey. This will help reduce the tartness from the cake.
Continue to cook and stir occasionally until the milk is a grainy consistency and the whey is evaporated. This will take an additional 15-20 minutes.
Add sugar and cardamom and keep stirring until the mixture starts coming together. This should take approximately 5 minutes.
Lower the heat to medium and cook for another 4-5 minutes until mixture changes to a slightly golden brown color.
Transfer mixture to the greased plate and press firmly into a square shape, approximately 1 inch high.
As an option, sprinkle sliced pistachios on top.
Let sit for at least an hour before slicing into individual pieces.
This wonderful dessert can be prepared ahead of time and stored at room temperature for a few days.