Combine coconut milk, sugar, vanilla extract, and salt in a saucepan. Bring to a boil and cook for 6 minutes, stirring occasionally.
Combine cornstarch and water in a bowl. Whisk until mixture has a uniform consistency.
Pour cornstarch-water mixture into the saucepan and whisk until mixture thickens into a pudding, about 2 minutes. Remove from heat and strain the mixture into a bowl.
Pour the strained mixture into a mold, pan, or individual serving glasses. Smooth out the surface and allow to cool about 15 minutes. Refrigerate for at least 2 hours. Sprinkle with ground cinnamon before serving.