Brownie Catastrophe

I would consider myself to be a pretty good cook. Things usually work out when I am cooking, and I can often come up with my own ideas & have them work, too.
However, there are occasional exceptions. One of those exceptions happened yesterday. I was in charge of making dessert for Sunday dinner and thought that brownies and ice cream would be a nice, easy way to go. I just picked up a boxed mix and a couple things of ice cream, thinking I would take the "easy" way out. As I was mixing them, I was tempted to substitute applesauce for the oil, but decided that as long as I was having brownies I would go ahead and make them the decadent way.
Well, I think I should have used the applesauce because when I pulled the brownies out of the oven, they were SWIMMING in oil. I literally POURED 1/4 cup of oil from the top of the pan (and the recipe only called for 1/2 cup of oil. I don't have any idea what happened, but it left me with 40 minutes to figure out a new dessert and get it made before we needed to leave. Happily, I came up with something that seemed to be acceptable. I have a recipe for a fresh peach dessert that is yummy, and although I didn't have any peaches, I did have a whole bunch of strawberries, so we had fresh strawberry dessert instead.
It was a fun change, but I am still wondering what on earth would have made my brownies separate the way they did. Oh well!