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 simmer for 25–30 minutes, stirring frequently. Cook 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 and mixture is smooth.
04 - Whisk egg yolks in a separate bowl. Gradually ladle 3–4 spoonfuls of hot rice mixture into yolks while whisking constantly to temper eggs and prevent curdling.
05 - Return tempered yolk mixture to saucepan. Cook over low heat, stirring continuously, for 2–3 minutes until custard coats the back of a spoon. Do not allow to boil.
06 - Pour custard into individual ramekins or a 9-inch baking dish. Smooth surface with a spoon.
07 - Mix remaining 2 tablespoons sugar with ground cinnamon. Sprinkle evenly over custard surface.
08 - Let custard cool to room temperature for 1 hour. Refrigerate for at least 2 hours before serving, or enjoy warm.