My favorite cake in the world is made on South Temple in Salt Lake City at Mrs. Backer's Pastry Shop.
The butter cream frosting is incredible and when paired with their pineapple filling it is near nirvana. When I visit Salt Lake, Mrs. Backer's is on my way to my mother's, so I try to stop if it is open. The first item on my list is the Hawaiian Bar, a butter cream-topped, pineapple filling filled cake-bar that I dream for. The Rum Bar also has pineapple filling and is a good second choice.
This past trip I could not resist a cupcake made of butter cream. It was a little much for me, I discovered that even I can be overwhelmed by butter cream. Mrs. Backer's offers way more stuff, really good stuff, but this was from my recent visit. The stuff of dreams.