Mix together sugar, flour, and salt, and add enough hot milk to make a thin paste.
Stir paste into hot milk and cook over low heat, stirring constantly for about 15 minutes.
Add some hot mixture gradually into beaten eggs, then return to pan.
Cook over low heat, stirring until mixture thickens slightly, about 2 minutes.
Don't cook longer - the eggs may curdle!
Cool quickly in the refrigerator.
Once cool, add vanilla and cream/half & half.
Pour into freezer canister; it will be about ⅔ full.
Freeze as you normally would. (recommend following your ice cream maker directions).