Mix together the cornstarch and 1/2 cup water (or milk, for richer taste) in a small bowl. Set aside.
Combine all remaining ingredients in a sauce pan EXCEPT for cornstarch slurry.
Heat the saucepan on medium-high until beginning to steam, stirring constantly with a whisk to avoid burning.
Gradually add cornstarch slurry from the separate bowl as you whisk.
Lower heat to medium & continue whisking until it thickens into a cream.
Turn off the heat and pour the cream (“gushta”) from the saucepan into another heat-proof container. Allow to cool for 15 minutes at room temperature uncovered.
Press saran wrap on top of cream (to avoid a skin being formed).
Place the container in the fridge until cold, firm, and ready to use (at least 3 hours).