Background: I can not fit 2 - 12 muffin tins in my oven in a manner that will result in 24 nicely baked muffins or cupcakes. I am using everyday muffin or cupcake recipes that use baking powder and or baking soda. Can I leave half the batter on the counter or in the refrigerator for the 20-30 minutes it takes to bake one batch without losing a significant amount of leavening power?
Yep! I make double-batches of mini cupcakes that often take 3-4 rounds in the oven and they all come out pretty much the same. Granted, the minis only bake for about 15 minutes or so and muffins can take longer but I've never had an issue.
As a note, the recipes I use call for either baking powder only or baking powder and baking soda.
Also, I usually make my cupcakes using full-cake batters, not cupcake-specific recipes.
As some other sources go, here's a similar question on The Kitchn and most of the answers seem to agree, there's generally little negative results from leaving the batter out for a short period of time:
Q: If I make 24 cupcakes from a layer cake recipe and I only have one 12 cupcake pan, can I let the batter sit for 30 minutes while the first 12 bake? Or should I put it in the fridge so the leavener is still active? Or divide the recipe and make it twice? Thanks!
Some selected answers:
It depends on the recipe. Most boxed mixes don't seem to differ, but I've noticed that my scratch-baked cupcakes tend to dome if I let them sit out before baking. Sometimes I do this on purpose if it fits my decorating idea better.
i have two 6 cupcake pans so im in the same boat, i always just leave it out and they seem to cook up fine
I let the batter sit out and I've never had a problem with the rise of the 2nd batch.