Preheat the oven to 375°F.

Line a baking sheet with aluminum foil and spray with nonstick cooking spray. Set aside.

Using clean hands, carefully remove the stems from the mushrooms and discard, or save for an alternative use.

Arrange the mushrooms on the baking sheet with the cavities facing up. Set aside.

Finely mince the scallion.

Place the crab meat, cream cheese, Parmesan, scallion, parsley, Old Bay seasoning, and garlic powder in a large mixing bowl. Set aside.

Place the crackers in a zip-top bag. Using a rolling pin or the bottom of a heavy glass, crush the crackers into coarse crumbs.

Add the cracker crumbs to the mixing bowl.

Using clean hands, mix until thoroughly combined.

With a small spoon and clean hands, stuff a generous tablespoon of filling into each mushroom. Pack the filling tightly, using enough so that the mushrooms are domed with stuffing.

Bake mushrooms on middle rack of oven until stuffing is nicely browned, 24-27 minutes.

Check to see that mushrooms are done. Remove from oven or add time as needed.

Allow the mushrooms to cool for 5-10 minutes before serving. Garnish with fresh thyme if you like. Leftovers may be refrigerated for up to two days.