Canned pineapple rings preserved in juice (it’s better than pineapple rings in syrup) is best choice. Fresh pineapple will not work for this mini cake recipe for many reasons. When fresh pineapple ring bakes, it’s fibrous and don’t turn caramelized as it’s not soaked in juice or syrup. Definitely use canned pineapple rings. If pineapple rings don’t fit the muffing trays you are using, check the above trick mentioned.