Rinse the Short-Grain White Rice under cold water until the rinse runs clear to remove excess starch.
Place the rinsed rice and Water in a heavy-bottomed saucepan, bring to a gentle boil, then reduce the heat and simmer, uncovered, until the rice is tender and most of the water is absorbed (about 15–20 minutes).
Pour in most of the Whole Milk and return the pan to low heat; stir frequently and simmer gently so the mixture becomes creamy without sticking or boiling over.
Stir in the Granulated Sugar and continue cooking until the sugar is completely dissolved and the pudding is sweet and smooth.
In a small bowl, whisk the Cornstarch with the reserved splash of cold Whole Milk to make a lump-free slurry, then slowly whisk this into the simmering pudding to thicken; cook for 1–2 minutes more until slightly glossy and thickened.
Grate a little zest from the Lemon into the pot and stir to brighten the flavor—if you like, add a teaspoon of lemon juice for extra tang, but avoid adding too much or it will curdle the milk.
Remove the pan from the heat and let the pudding cool for a few minutes, stirring occasionally; if it becomes too thick, stir in a little more Whole Milk to loosen to your desired consistency.
Spoon the rizogalo into serving bowls, sprinkle with Ground Cinnamon, and serve warm or refrigerate until chilled. The flavors deepen after chilling, and a final dusting of cinnamon before serving is lovely.
