Put oil in the pan for deep frying. Keep the heat very low. (See notes)
Add milk powder, baking powder and plain flour in the mixing bowl and mix them together.
Add melted butter and egg. Mix it gently using hands.
The dough will come together and will have sticky consistency. (See Notes)
Roll the dough into log shape and cut 12 small portions. Leave a tiny bit of dough which we will be used to test the temperature of the oil.
Grease your palms with cooking oil and roll the balls. Make sure there are no cracks.
Put a tiny tester ball in the oil to check the temperature of the oil. (See Notes) You should see that tiny ball will sink to bottom and there should be bubbles around it. And after few seconds it starts to float. This means that oil temperature is right.
Once all balls are rolled out put them in oil together. At first they will sink but will start to float as they are cooking.
Gently use frying spoon to rotate them ensuring they get nice colour evenly.
Strain them with frying spoon and put them immediately into sugar syrup. Make sure the Sugar syrup is not cold. (See Notes)
Once all Gulab jamuns are in the syrup cover the pan with lid and allow them to soak the syrup.
Dish it out gently in your serving tray. (See notes) Sprinkle them with finely chopped pistachios.