01 - Combine rice, whole milk, heavy cream, lemon peel strips, cinnamon stick, and salt in medium saucepan. Bring to gentle simmer over medium heat, stirring occasionally to prevent sticking.
02 - Reduce heat to low and cook 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 2–3 minutes, stirring until sugar completely dissolves and mixture becomes glossy.
04 - Whisk egg yolks in separate bowl. Gradually ladle 3–4 spoonfuls of hot rice mixture into yolks while whisking continuously to temper eggs without curdling.
05 - Return tempered yolks to saucepan. Cook over low heat, stirring constantly, 2–3 minutes until mixture slightly thickens. Do not boil or eggs may scramble. Remove from heat immediately.
06 - Pour custard evenly into individual ramekins or one large shallow serving dish. Smooth top with spatula for even surface.
07 - Mix 2 tablespoons sugar with ground cinnamon. Sprinkle evenly over custard surface in light layer.
08 - Let custard cool to room temperature, about 1 hour. Refrigerate at least 2 hours for chilled serving, or serve slightly warm. Best enjoyed same day.