Cooked pineapple custard filling for layer cakes.

Steps

1. Combine flour, sugar, salt; add milk and juice. Stir until smooth.
2. Cook over medium heat until thickened.
3. Remove from heat. Add a little of the mixture to egg yolk, return egg yolk to saucepan.
4. Bring to the boil, stirring constantly over medium heat.
5. Remove from heat, stir in margarine, pineapple and lemon juice.
6. Cool and spread on layer cake.