01 - Combine rice, whole milk, heavy cream, lemon peel strips, cinnamon stick, and salt in a medium saucepan. Bring to a gentle simmer over medium heat, stirring occasionally to prevent sticking.
02 - Reduce heat to low and cook for 25–30 minutes, stirring frequently, until rice is tender and mixture has thickened considerably. Remove and discard lemon peel and cinnamon stick.
03 - Stir in granulated sugar, unsalted butter, and vanilla extract. Continue cooking for 2–3 minutes, stirring until sugar completely dissolves.
04 - Whisk egg yolks in a separate mixing bowl. Gradually ladle small amounts of hot rice mixture into yolks while whisking continuously to temper eggs and prevent curdling.
05 - Return tempered yolk mixture to saucepan. Cook over low heat, stirring constantly, for 2–3 minutes until custard thickens slightly. Do not allow to boil.
06 - Pour custard evenly into individual ramekins or a large shallow serving dish.
07 - Mix remaining 2 tablespoons sugar with ground cinnamon. Sprinkle evenly over surface of custard.
08 - Allow rice custard to cool to room temperature before serving. May be served warm or refrigerated and served chilled.