I was making scratch chocolate cupcakes and I read on here that you are to put only one tray of cupcakes in the oven at a time. So, while I waited for the first tray to be done, the batter sat. When I went back to the batter to fill the second tray, there were a couple bubbles on top of the batter. Is that normal? Why does that happen?

Thanks!

The bubbles are caused by your leavening agent (baking powder/soda) starting to act. This is normal. Depending on the recipe you are using and the time it takes for each batch to bake you might consider refrigerating the batter. The refrigerated batch will take longer to bake so this does introduce other factors... am opening a whole new can of worms here

I have experimented with this sort of thing over the years and have noted what works and what doesn't - refrigerate or not, bake two trays or one - for my various favourite cupcakes recipes (I am a scratch-only baker). Therefore I can't tell you what method to use unfortunately but something to consider nevertheless.

Thank you so much!

This was my first time making from scratch and I worried I'd messed it up!