Set the Instant Pot to saute(normal) mode and heat ghee. Add grated dudhi and sauté for a minute. Add 1/2 cup of low fat milk. Close Instant Pot with Pressure valve to sealing. Cook on Manual(Hi) for 2 mins followed by Quick Release (Natural Pressure Release works too).
Set the Instant Pot to Saute(normal) mode. Mix the milk powder in remaining half cup of milk and add it to the Instant Pot.
Add sugar and cook for 5 minutes stirring frequently until most of the liquids evaporate and the halwa thickens. If the halwa starts to splutter set the Instant Pot to Saute(Less) mode and continue to cook for another 5 minutes.
Stir in Vanilla, mix well and turn the Instant Pot off. Halwa will thicken further as it cools down. Garnish with sliced almonds. Enjoy warm or chilled.