Doubling a recipe should be as simple as multiplying every ingredient measurement by two, right? Well, not always. If you’ve ever found yourself in the midst of a frustrating recipe-doubling mishap, here’s why it’s not always as straight-forward as it seems.
First of all, let’s get the elephant in the room out of the way: Mental math doesn’t always work out, no offense to your brain power. It’s really easy to scan down a recipe and think you’ve quickly sorted out how to alter the ingredients to fit a new scale, but it’s equally easy to make a mistake if you don’t write the new measurements down. Re-writing the recipe you need to alter, with new measurements, is the best place to start this journey to ensure success no matter how many people you’re feeding.
Aside from simple math mistakes, it’s also important to remember that cooking and baking, while both predicated on chemistry, are extremely different. Cooking leaves more room for modification and improvising while baking is a sensitive and chemical-reaction-dependent pursuit.
In cooking, some ingredients are less sensitive to scaling than others. It’s usually safe to go ahead and simply multiply by two for base ingredients like vegetables, broth, and protein, but for flavor elements (like spices) it’s better to start by multiplying by 1.5 and then tasting and adjusting from there, especially if you’re not always precise about leveling off measuring spoons. Some flavors punch above their weight more than others—like salt or anything spicy—and in too large of a concentration, can really overpower a dish, whereas others that are more subtle—like parsley—won’t be too noticeable if you go overboard. Any alcohol in a recipe should also first be doubled by 1.5 and then adjusted from there if needed, with the same concerns about over concentrated flavors as with pungent spices.
For baking, a similar approach to base ingredients can be taken: Additions like flour, nuts, sugar, or dairy can usually be straight doubled. It’s baking soda and baking powder that can get weird. If they’re not in the exact right proportion as the original, your cake might fail to rise and turn out dense, or it’ll puff up to an unseemly degree and then collapse as soon it hits cold air outside of the oven. Because of this, the best approach to doubling a baking recipe is actually to just make two separate batches of the original recipe.
Lastly, remember to cover (or, in the case of cookie dough, chill) any extra ingredients you’re not done working with yet as you cook or bake. A doubled recipe means twice as much food to work with, which can mean butter that’s meant to be cold is now melting at room temperature toward the end of a batch of biscuits, herbs are drying out, etc. So remember, the best first step you can take towards successfully doubling a recipe is to write out your new amounts needed per ingredient and even measuring out each ingredient as you go.