Whisk sugar, cornstarch, and salt together in a 3-quart saucier. When no lumps of cornstarch remain, add exactly 14 ounces of the milk and whisk to combine. Cook over medium heat, whisking constantly but not vigorously, until it begins to simmer. This will take about 6 minutes, if the process seems to be moving slowly, simply turn up the heat. When the mixture comes to a boil, set a timer and continue cooking and whisking for exactly 1 minute. This ensures the cornstarch is fully hydrated.