Using the same article linked in this claim, there is actually direct textual evidence that the statement "Eating Ice cream for Breakfast Makes You Smarter" is blatantly incorrect. As much as I wish it was true, there is a quote about three paragraphs down that states "If you want to be smart (or have a long, healthy life) eating sweets every morning for breakfast is the last thing you should do." Earlier in the paragraph, the author also explains that sugar "in the long run...will increase your risk of depression, reduce your brain function, and make you more susceptible to Alzheimer's."
Also, there's no elaboration on what these "tasks" are that these subjects are performing. Additionally, the ability to "perform tasks" or have a faster reaction time by no means has any direct correlation to intelligence.