Grease a square cake tin or line with parchment paper.
In a heavy bottomed pan add ricotta cheese and start cooking it to evaporate water. In case you don't have Ricotta Cheese, take the same amount of fresh paneer. Avoid Store-bought Paneer.
Keep stirring cheese so that it doesn't burn in the pan. You can add a tsp of ghee(Indian Clarified Butter) or butter in it but is optional.
When the water dries up and Ricotta is little crumbly not dry, add condensed milk and cardamom powder.
Cook on medium flame, continuously stirring the mixture taking care it doesn't burn the bottom.
When the mixture starts getting thick divide the mixture in two parts.
Melt both the chocolates separately in the microwave or double broiler. OR you can grate it, if you are using chocolate blocks.
In one part add white chocolate and mix well. This is our bottom layer. Transfer this to the greased pan and level the surface.
To another part, add the dark/milk chocolate and mix well. Add sugar if you are using dark chocolate (as per your taste) to adjust the sweetness. This is optional, I didn't add any sugar as I like to keep my desserts and sweets moderately sweet.
Transfer the chocolate part over the white part and level it well.
Garnish with chopped pistachios and refrigerate for at least 3-4 hrs.
Once set cut into square pieces and serve or store in an airtight container