Cook sago with plenty of water (about 5 to 6 cups) until it turns translucent. Drain well and add cold water to avoid sticking. Keep aside.
In a pan, combine chopped pineapple and 1 tablespoon sugar. Cook for few minutes or until it turns almost dry. Allow this to cool completely. Keep aside.
In a heavy bottomed pan, combine milk and condensed milk. Bring it to just under a boil.
Now add cooked sago pearls and sugar to taste. Mix well and cook for few minutes, stirring continuously until it turns slightly thick. Allow it to cool completely.
Once it has cooled, add the cooked pineapple and mix well.