Place parchment paper over a plate that is 8-inches (20 cm) in diameter, or grease the plate with unsalted butter.

Next, add the butter to a medium-sized, heavy-duty pot over medium heat.

Add in the ricotta cheese, sweetened condensed milk, stirring with a wooden spoon or rubber spatula until the mixture comes to a boil.

At this stage, reduce the heat to a low flame and let the mixture cook, stirring occasionally for 10 minutes.

Add in the cocoa powder, salt and cardamom, and continue cooking the mixture until it has reduced in volume and has thickened significantly. The texture should resemble that of ricotta cheese (before you mixed it with everything), and should start to leave the sides of the pan. This will take about 20-25 minutes, but it can take longer depending on your heat.

Remove the mixture from heat, and press into a square shape using the rubber spatula, until it is around 6-inches (15 cm) in diameter (the mixture will be hot so do this carefully).

Sprinkle and press down the pistachios on the top, then refrigerate the kalakand until it has solidified, for around 1 hour.

Cut into small squares (I do 5x5, so 25 squares) and serve. This keeps well for a week if stored in an airtight container in the fridge.