For best results, use cold butter to get a nice crunchy and golden top on your pineapple dump cake. You can use either crushed pineapple or pineapple tidbits, and if your pineapple is in syrup, just drain some juice before using. Adding lemon juice is optional but helps make the pineapple taste fresh and bright. This recipe is very easy, perfect for beginner cooks, and great when you need to feed a crowd or want a quick, delicious dessert.