So you're in a rush because you forgot about that bake sale at 9am tomorrow. You decide to whip up some cupcakes because you have boxed mix in your cupboard.
Halfway through the baking time, you open the oven to see how it's doing and they look GREAT! The timer goes and you open the oven again and...they're flat?? How did that happen??
We have all fallen victim to the flat baked goods predicament, but what exactly is happening? You followed the recipe exactly!
I'll tell you exactly what happened: you opened the oven.
When you open the oven halfway through baking it, you let a ton of cool air inside, which ultimately affects the rising of your baked goods. When the oven door is open for just 30 seconds, the temperature can drop 150 degrees. Then, it takes another few minutes to get it back up to the desired heat when you close the door.
The same principle applies for any cooking. Have you noticed the roast you're cooking is taking forever? Have you also noticed you've been opening the door every few minutes to check the temperature? There's your answer.
The fix is pretty simple: make sure you have an oven light that works! That way, you don't have to keep opening up the door to check on your treats.