From the movie, The Founder please answer this question:

Kroc has dinner with one of his franchisees, Rollie Smith and his wife June. They share an idea with him on how they can save hundreds of dollars in electrical costs and reduce time in making milkshakes. They say that the walk-in refrigerator and ice cream, is costing them a fortune. What is the solution, What is Kroc's response, and what happens when he calls the McDonalds brothers to pitch the idea of the milkshake mix to save costs, do they agree?