Serious Eats - seriouseats.com

I was in middle school. I was into baking when I got home from school, even had my own cookbook for kids. There was a recipe for an all-purpose baking mix, which you could then use to make cookies, cakes, pancakes, etc.

I wanted to whip up a cake, so I started with the base. Halfway through, I called my mom at work and told her to bring home a bag of flour, as I didn't have enough to finish my mix.

"But," she said, "I just bought an entire bag. Look in the pantry."

I had looked in the pantry...and used that entire bag. I had neglected to read how many servings the mix would produce. Instead of one cake, we had enough mix to make about 50. Which wouldn't have been a problem if I hadn't used too much baking soda. Every one of those cakes tasted like crap...