Brownies are usually so delicious, that it seems impossible that you'd have leftovers. But if you do end up with part of your pan left (or if you have the forethought to make a bunch to enjoy later), you'll want to know exactly how to store your brownies so they don't go stale.
Air is the enemy of freshness for most baked goods, and brownies are definitely included. Using airtight wrappings (including using plastic wrap right against the brownies) is key to keeping your brownies fresh, whether you're keeping them at room temperature for short-term storage, or planning to freeze them so you can have a fresh brownie ready whenever you need it.
How to Store Brownies at Room Temperature
Brownies should be wrapped tightly in plastic wrap, and placed in an airtight container to help keep them from drying out and going stale. (You can also use a layer of aluminum foil around the layer of plastic wrap to help protect them from air exposure.)
Brownies can be kept at room temperature for up to five days for most brownie types.
A cheesecake swirl or frosting or a ganache frosting should not be kept at room temperature. Store brownies in the fridge if they contain add-ins that are normally refrigerated.
How to Store Brownies in the Refrigerator
Brownies can last even longer in the refrigerator—up to two weeks. Again, you'll want to wrap in plastic wrap and place in an airtight container, to help reduce the air exposure and the exposure to any odors and flavors in your fridge. (No one wants oniony brownies!)
When you're ready to enjoy, take them out about an hour before serving to warm up to room temperature, or go ahead and warm them up in the oven or microwave.
How to Store Brownies in the Freezer
Brownies can last for months in the freezer, though for ideal freshness, it's best to enjoy them within two months of hitting the freezer. To protect your brownies from freezer burn it's important (yet again!) to keep air away from the brownies. Wrap brownies tightly in freezer-quality plastic wrap or a freezer-friendly bag with the air pushed out of the bag. You can wrap it in a second layer of foil or place it in a freezer-friendly container as a second layer of protection.
Again, you should remove the brownies a couple of hours before you're ready to enjoy, or use your oven or microwave to bring the brownies back to their fresh-baked glory.
Every surface exposed to air is another opportunity for freezer burn to set in. You can store the brownies in larger hunks to prevent freezer burn, then cut them into single servings for reheating after they thaw.
How to Warm Up Your Brownies
Brownies will stay fresh if stored properly in an airtight container, but they won't have that fresh-from-the-oven goodness the next day. So it's worth taking a few minutes to reheat your brownie to bring back that warm, gooey feeling.
For the best and most consistent results, warm up a brownie or two at a time—larger slabs of brownie may start to dry out around the edges before they become sufficiently warm in the middle.
Reheat a brownie in a microwave
You can reheat them in the microwave for about 20 to 30 seconds per brownie (err on the higher side if reheating from the fridge or freezer). If you want to ensure that your brownie stays moist (or add more moisture to a dry or stale brownie), cover it in a damp paper towel while it cooks.
Reheat a brownie in the oven or toaster oven
The oven or toaster oven is the best way to reheat a larger portion of brownies. (Pre-cut the brownies and space them out a bit on the pan so that they can heat more evenly.) Bake at 350 degrees for 5 minutes for a couple of brownies, or 15 minutes for a larger amount.
