Slivered, chopped or crushed pistachios, to garnishoptional
Grease a 23 x 15 x 5cm (9" x 6") tin with oil.
In a large, nonstick pan, heat together the ghee and milk. Bring to a gentle simmer but do not boil. Turn the heat down to low.
Once hot, add the milk powder and icing sugar. Beat with a wooden spoon until smooth. Any lumps will disappear as it cooks.
Cook over a low heat until smooth and glossy, about 10 minutes. Stir all the time to ensure the mixture does not burn.
Stir in the pistachio butter and continue to cook for a further minute. The burfi is done when it is glossy and reaches 118°C/235°F on a sugar thermometer. If you do not have a sugar thermometer, place a small amount of the mixture onto a very cold plate (keep one in the fridge) and if you are able to roll the mixture into a soft ball, it is ready.
Remove from the heat and immediately stir in any food colours (if using). I used a combination of blue and green gel good colours to achieve a natural pistachio colour. A small amount of blue neutralises yellow tones from the caramelised milk powder for a more vivid pistachio hue. Food colour is optional. You do not have to add it if you don’t wish to.
Pour the hot burfi mixture into the greased tin. Flatten the top down using the back of a spoon. Try to get the surface as even as possible. You can lightly grease the spoon with oil if it helps create a smooth surface. If you’re not using gold/silver leaf, you can press a small handful of crushed or slivered pistachios into the surface of the burfi at this stage.
Allow to set at room temperature for 3-4 hours.
Top with optional gold/silver leaf for an Indian mithai shop finish.
Use a large, sharp knife to cut the burfi into pieces. I cut mine into 12 squares but you can cut these as small as 1cm x 1cm if you like. These tiny squares are perfect with coffee after dinner.