Leftover Mashed Potatoes Are Perfect For Savory Tender Biscuits

If you end up with leftover mashed potatoes after a holiday feast or dinner party, it can seem like a chore to get through them all. Reheated mashed potatoes can be dry and unappealing, and using them in something like a Thanksgiving leftovers shepherd's pie will probably only create more leftovers. The best way to use up leftover mashed potatoes — that's also a crowd-pleaser — is to make savory, tender buttermilk biscuits.

Mashed potato biscuits offer the best things you like about biscuits and mashed potatoes — tender, flaky layers, and fluffy, buttery potatoes — and combine these elements in a neat little package. They're also customizable, as anything from cheese to herbs goes extremely well on this blank canvas. The finished result is biscuits that are moist while still being flaky and super tender. Plus, they're ideal vessels for anything from a fried egg to a swath of butter drizzled with hot honey to a leftover turkey sandwich topped with tart cranberry sauce.

Mashed potato biscuits practically make themselves and only call for a few pantry staples like flour, buttermilk, baking powder, and baking soda. When it comes to what mashed potatoes you use, it can be any leftovers you have. For this purpose, fatty, delicious mashed potatoes loaded with butter and cream will work, as will plain mashed potatoes. All you need to do is gently crumble them into the dry ingredients so everything gets evenly incorporated. 

After mixing the dry ingredients, grate ice-cold butter into the bowl and handle it as little as possible so the biscuits stay fluffy. For liquid ingredients, if you don't have buttermilk, don't resort to mixing milk with acid to create a substitute, as it won't provide the acidity or thickness you need. Instead, you can use plain yogurt, kefir, or sour cream.

Leftover mashed potato biscuits are also an opportunity to use up other ingredients you have lying around in the refrigerator. For example, leftover fresh herbs from roasting your turkey or chicken can be finely chopped and added to the dry ingredients. If you're hoarding a few blocks of cheese, like cheddar or Gruyère, you can grate them into the dry ingredients and give them a toss to coat them with flour.

Why do potatoes work for super moist and fluffy things? Because of the humble tuber's high starch content. This is why things like potato bread are so soft, fluffy, and craveable: Potato flakes are the key ingredient. When we add potatoes to biscuit recipes, whether it's mashed potatoes, potato flakes, or potato flour, we're taking advantage of the abundant starches. The starch in the potato plays the part of gluten, even though potatoes have no gluten, meaning the starches absorb liquids and provide structure. 

Potato flour and mashed potatoes rival wheat flour's ability to absorb moisture. So, when it comes to biscuits, adding leftover potatoes doubles down on the dough's ability to hang on to its moisture content. We don't need to add ingredients like milk or butter to enrich and soften bread dough since the potato performs this job.

You can use mashed potatoes in recipes by keeping them to a specific ratio, as loaves of bread with too much potato can turn out gluey. Ideally, ¼ cup of mashed potato for every cup of flour, and reducing your liquids by half should yield the most delicious results.