Chocolate Filling won’t thicken

This is my recipe. I cup sugar, I cup hot water, 2 heaping tablespoons powdered baking chocolate, 2 heaping tablespoons cornstarch. Mix together, add hot water over medium/high heat, keep stirring until thickened, add tsp butter at the end. Put in the fridge to cool and thicken. This goes in between 2 chocolate cake layers. It always ends up running out of the cake. HELP!!


Nancy October 7, 2021
Another thought.
If this recipe always turns out runny, maybe the problem is with it and not with your technique.
Perhaps look for a tested, reliable recipe that is thicker and more spreadable. Something like a ganache, with more chocolate and less liquid/dairy.
Happygoin October 6, 2021
Are you bringing your mixture to a full boil? In order for cornstarch to thicken properly, it needs to come to a full boil. When it does, let it boil for 15-30 seconds or so. Stir it constantly with a wooden spoon or spatula so it doesn’t stick to the bottom of your pan. I hope this helps.
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