In top of double-boiler mix sugar, flour and salt.

Whisk in 1 cup of the milk until smooth.

Bring to a boil over medium heat, stirring briskly.

Continue to stir and let boil until smoothly thickened (about 2 minutes).

Remove from heat.

With fork, beat eggs with remaining 1 cup of milk.

Gradually stir into hot mixture.

Return to heat and bring to a boil.

Stir and boil until mixture thickens (about 1 minute).

Remove from heat and stir in margarine and vanilla.

Add 1/2 cup of semi-sweet chocolate chips and stir until melted.

Spoon into prepared pie crust and cool.

Serve with real whipped cream.

For banana cream pie, omit chocolate chips, and slice 2 or 3 bananas into bottom of prepared pie crust and top with the pudding.

For coconut cream pie, omit chocolate chips, and stir in 1/2 cup of coconut.

I've never tried this, but it's on my list of things to do: stir in 1/2 cup of peanut butter (or peanut butter chips, I guess) for peanut butter cream pie (omitting the chocolate chips).