In a medium saucepan, combine the cooked rice, milk, sugar, and salt. Cook over medium heat, stirring occasionally.

While the rice mixture is heating, in a small bowl, beat the egg until well mixed.

Once the rice mixture is warm and begins to steam, slowly pour half a cup of the rice mixture into the beaten egg, whisking constantly to temper the egg.

Gradually add the tempered egg mixture back into the saucepan with the rice, stirring continuously.

Cook the mixture over medium-low heat for about 20 minutes, or until it thickens to a creamy consistency, stirring frequently to prevent sticking.

Remove the saucepan from the heat and stir in the vanilla extract and cinnamon. If using raisins, fold them in now.

Serve the rice pudding warm, or let it cool and then refrigerate to serve chilled. Sprinkle with a little extra cinnamon on top before serving, if desired.