You can store any leftover cooked stuffed mushrooms in an air-tight container, in the fridge for 3-5 days. I like to reheat them in the microwave, just for a few seconds. You can also cover them with foil and rewarm in a 250 degree oven. To reheat, you can use a microwave to reheat the mushrooms for a few seconds or in an air fryer.  They are best enjoyed the first day.