He wasn't getting the hint. He might never get the hint, if he doesn't explain it in blunt detail that he doesn't want to have any sort of lecture right now. Maybe his face says it all, with the slightly annoyed expression on his face, the way he turns his chin up at him, glares up at the taller boy.

"Now is not the time." Riddle states, his tone firm. He motions to the pie, "Focus on the task I've given you first. Only after we've got everything ready and have passed out the pieces can we talk. Got it?"

Maybe that would work???