Grate the peeled carrots using the small holes of a grater. You can also grind them along with ¼~½ cup of milk into a smooth paste.
Soak raisins in water and set aside.
Melt ghee/ unsalted butter in a heavy bottomed pan on medium-low heat. Add the grated and ground cardamom. Cook until they are cooked through and tender, about 15~20 minutes, stirring occasionally.
While the carrots are cooking, combine ricotta cheese and powdered milk in a medium size bowl. Mix well into a smooth mixture without any lumps.
Add sugar to the carrots and cook till dissolved.
Stir in the the ricotta mixture and mix well. Cook gently until the mixture is thick and creamy, about 5~7 minutes.
Drain the raisins and add to the pan along with the other nuts. Mix well. At this stage, halva will have a soft consistency and can be served in a bowl.
If you want to make into squares/ diamonds, then cook till the mixture starts to leave the sides of the pan, about 10~15 minutes more. Then pour the mixture into a greased 9″ square pan and let chill to set, about 2~3 hours. Cut into pieces to petit four or burfi.