Drain the juice from the canned pineapple and chop them. Add 2 tbsp sugar to chopped pineapple and cook till the water is completely dried and pineapple becomes slightly mushy, but holding it's shape.Let it cool completely.
Dry roast the sago for 2 mins. Wash the roasted sago. Boil 2.5 cups of water in a deep and wide pan. Add washed sago and cook. Stir in between to avoid lumps. Cook till the sago becomes transparent and soft when pressed between your finger tips. The timing varies depending on the type and size of sago you use. Mine took around 25-30 mins.
Drain the water from the cooked sago and hold it in a sieve, under running water to remove the starch completely.
Heat together milk and condensed milk in a deep and wide pan. Bring it to a boil and reduce the flame. Keep stirring in between to avoid caramelising the milk at the bottom. When it boils, add cooked sago and continue stirring and cooking till the mixture thickens, 10-15 mins. Remove the milk sago mixture from the gas and let it cool. Even if the milk mixture doesnt thicken immediately, it will thicken as it rests.
Once the milk sago mixture is cooled to room temp, add cooked pineapple and mix well. Chill in the refrigerator for 3-4 hours. Serve chilled.