I just made this using 1/2 cup butter and 1/2 cup cream cheese. It's still in the oven. I'm a bit worried, though, because the batter was really thick - it didn't exactly "pour" into the buttered pan. I almost scraped it back out to add some cream, but decided to bake it as is. I've set my timer for 40 minutes, just in case. I'll report back.