01 - Combine rice, whole milk, heavy cream, lemon peel strips, cinnamon stick, and salt in a medium saucepan. Bring to 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, butter, and vanilla extract. Continue cooking for 2-3 minutes, stirring until sugar completely dissolves.
04 - Whisk egg yolks in separate bowl. Gradually ladle 2-3 spoonfuls of hot rice mixture into yolks while whisking continuously to gently warm them without curdling.
05 - Return tempered yolks to saucepan. Cook over low heat, stirring constantly, for 2-3 minutes until mixture coats spoon slightly. Do not boil or eggs may scramble.
06 - Pour custard evenly into individual ramekins or one large shallow serving dish.
07 - Mix remaining 2 tablespoons sugar with ground cinnamon. Sprinkle evenly over surface of custard(s).
08 - Let custard cool to room temperature, about 1 hour. Serve warm or refrigerate until chilled, at least 3 hours.