1) In a large saucepan, add in the crushed pineapple with some water and let it come to a boil. Add in the butter and stir well.
2) Remove the saucepan from the flame and set aside.
3) In a bowl, beat the eggs till light and frothy. Add in the mix of flour and sugar into the eggs and beat once more to mix well.
4) Add the egg mixture to the pineapples and put it back on the double boiler. Cook till the mixture turns thick. Let chill for a few hours.
5) Pour the filling into small tart shells.
6) Garnish the tart shells with cool whip and small slices of pineapple, if desired.