CAN CRAB STUFFED MUSHROOMS BE FROZEN? Yes, you can freeze crab stuffed mushrooms before baking them to save time with prep on the day you are serving them. To freeze, clean and fill your mushrooms according to the instructions in the recipe. Instead of baking them, place them on a baking sheet and put them in the freezer for 30 -60 minutes, until they have frozen. Take the mushrooms off the baking sheet and put them in a gallon freezer bag. Remove as much air as possible from the bag before sealing tightly.