Using a wooden spoon, stir the mixture constantly until it's thick and a thin film forms on the bottom of the pan, 4 to 5 minutes. (tastingtable.com)
Stir vigorously until film forms on bottom of pan and dough is no longer sticky, 1 to 2 minutes longer. (epicurious.com)
Return to heat; stir vigorously over medium heat until mixture forms a ball and a thin, dry film forms on bottom and sides of pan, about 1 minute. (epicurious.com)