Yes, while it is best not to freeze raw mushrooms, you can freeze them after you roast mushrooms. Let them cool to room temperature, then freeze in a single layer before transferring to a plastic zipper storage bag or an airtight container. They will keep for two or three months. When you are ready to use them, thaw in the refrigerator, then toss on a pizza, stir into pasta, maybe even with this vodka sauce, or heat them up to serve as a side dish to some steak bites with a baked potato.