I'm planning on baking a pineapple cake for my husband's birthday and the only recipes I find are for pineapple upside down cake. Can I use a pineapple upside down cake and just add the pineapple on top to the batter instead? Has anyone tried this before?
As Aaronut said, it'd definitely be best to just find a pineapple cake recipe.
But if you have a pineapple upside down cake recipe that you're really attached to, you could always just try it, presumably cutting the pineapple into smaller chunks. Depending on the batter, though, the pineapple may tend to either sink or float.
A pineapple upside down cake is normally just plain cake batter baked on top of a layer of sugar and pineapple. The sugar and pineapple (which also has a lot of sugar) form a caramel from being in contact with the hot pan, thus making the awesomeness happen when you flip it over. If you just bake the pineapple on top, you won't get this effect, nor will you get the taste of the pineapple in the cake. You'll probably just end up with kind of dry and chewy pineapple slices on top of a plain cake.
You could probably do something fancy like pureeing and draining the pineapple, adding that to the batter, then reducing the juice to a syrup and pouring that over before decorating it. By the time you do all that though, you'd probably be better off just finding a recipe for a pineapple cake.