How do I get my puppy to stop eating cat food?

So my 5 month old puppy Dante has decided he likes the cats food. I bought this special enclosure thing specifically for the cats and he’s gotten big enough and figured out how to get his head into it/ lick through the bars. I tried putting their food on the counter top but I’m learning that he’s definitely mixed with a Great Dane because he can get the food there too. I’m at a loss for what to do at this point and how to get him to stop eating their food.