The Roland Garros runner-up asked for the treats to be brought to the court and seemingly took energy from the pause before dispatching Paul, who had himself eliminated top seed Alexander Zverev 24 hours earlier.
"A sweet with chocolate makes me happy," Cobolli said. "I've tried it in doubles so why not singles?"
Cobolli mounted the comeback after dropping the opening set against Paul, one of four US men in the last-eight stage.
With the match tied at a set apiece, the American needed an extraordinary effort to hold serve for 4-3 in the final set, battling through five deuces and saving four break points.
But Cobolli ignored the showing as he closed out victory.
"It was a difficult day," the winner said. "I'm proud of my effort, my game and my mental strength. It is all good practice for the US Open.
"My shape is 100 percent. I may play golf tomorrow on a day off to relax but I will be ready to fight again."
Cobolli is the 11th different Italian to reach a Masters semi-finals since the series began 36 years ago.
His unusual candy break was somewhat reminiscent of the espresso shots often downed in the heat of battle by his compatriot Luciano Darderi.
Cobelli will play for a place in the final when he faces Arthur Fils, who defeated Thiago Tirante 6-3, 6-2 in just 64 minutes - the shortest men's match of the event.
Fils, the eighth Frenchman to reach Cincinnati semi-finals in the Open Era, said he was impressed by the weight of his opponent's big game.
"He has an unbelievable serve, I was surprised by the speed of his ball," he said.
"I tried to make him play a bit more. I stayed solid in my head and it worked pretty well for me."
