Mix the cornstarch with some of the milk in a separate bowl until all clumps dissolve.
In a pot, combine the rest of the ingredients and bring to a simmer. Add the cornstarch mixture and cook for about a minute until thickens. Pour into serving containers (makes 2), and chill until desired firmness is achieved.
To make the syrup, microwave the ingredients to dissolve the sugar. Let cool.
Pour over chilled pudding and top with crushed pistachios.