Take 4 cups of milk into a heavy bottom saucepan and turn the heat to medium. Let it come to a simmer.
Meantime, mix remaining ¼ cup of milk and custard powder in a small bowl and make a lump-free mixture. Keep it aside till needed.
Back to the milk. While it is simmering, do stir the milk very frequently. Make sure that milk is not sticking to the sides and bottom of the pan. Stay nearby, do not leave simmering milk unattended even for a few seconds, it may overflow. Simmer till it becomes almost half of its original volume. It takes around 25-30 minutes.
Now add sugar, custard powder mixture, and khoya.
Mix and let it simmer for 4-5 minutes or till the milk thickens really well like custard consistency. Remove it from the gas heat and let it cool down to room temperature. While cooling, it may set the film on top of the mango kulfi mixture. Use a whisk and beat it to break the lumps.
Mix in heavy cream and mango pulp.
Pour into the kulfi molds. Cover with foil, make a hole and place the popsicle sticks inside. Freeze it overnight or till frozen.
To unmold, dip the kulfi mold into the glass of room temperature water and it will slide out easily. Make sure that water does not go into the kulfi.
Garnish with chopped pistachios and serve immediately.
Milk: I highly recommend using full-fat whole milk. Khoya: It is available in the frozen section of Indian grocery stores. In the absence of it, you can use milk powder.
Mango pulp: I have used canned alphonso mango pulp that I bought from the Indian store. You can use fresh pureed mango or pureed frozen mango cubes.
Sugar: My canned mango pulp if already sweetened. If using fresh mangoes then you need to add more sugar to sweeten the pulp while grinding.
Pistachios: I have used that as a garnishing. But if you like to bite into the kulfi then add into the kulfi mixture before freezing.
Flavoring: I have kept my mango kulfi plain, dominant mango flavored. But for the variation, you can add a pinch of cardamom powder (add at the end to retain flavor and aroma) or saffron (add while simmering the milk).Recipe notes:
It is important to stir the milk (scrape the sides and bottom of the pan) while milk is simmering. It prevents scorching and burning the milk. If milk does burn, it will ruin the taste.
You cannot leave the simmering milk unattended. Milk has the nature of overflowing while it is boiling. So stay there and keep stirring.
After adding the custard powder mixture, it starts thicken really fast. Keep an eye on it.
Always let the kulfi mixture cool down completely to room temperature, then add mango pulp. So it retains the fresh mango flavor. Never add to warm or hot mixture.