Ice Cream Mixture Suddenly Became VERY THICK While Heating. Help
I'm making ice cream, and while heating the mixture over the stove, it suddenly turned really thick before ever reaching a boil. What did I do wrong, and should I toss it?
The ingredients were added as follows:
Sugar and cornstarch were mixed together, then heavy cream, milk, and agave syrup were added to mixture. The heat was turned on to low medium and stirred slowly and constantly with a whisk. Tiny air bubbles appeared, likely from stirring. Suddenly, while mixture was warm but never bubbled, the whole thing because REALLY thick and paste-like...similar to the consistency of tooth paste. I tried to strain it, but it wouldn't go through the sieve. I put the whole thing into a bowl, covered it with wax paper, and put it in the fridge to consult the internetz.
My questions are:
Why didn't it ever bubble or boil?
Is adding the corn starch before the milk and cream an issue?
Should I lessen the amount of agave syrup used? (I substituted 1/4 cup agave syrup for 1/2 cup corn syrup) Should I add 1/2 cup milk to make up for the difference here?
The whole mixture was nice and thin...until it wasn't. What role does heating play in making the mixture? Is bringing it to a boil necessary?