Preheat your oven to 400 degrees F. Line a large baking dish or cookie sheet with aluminum foil and spray evenly with nonstick cooking spray. Remove the stems from the mushrooms and arrange them stem-side-up in the baking dish.

Roughly chop the surimi into small pea-sized pieces.

In a large bowl, mix the surimi, parsley, scallions, Parmesan cheese, bread crumbs, garlic powder, salt, and pepper. Add the mayonnaise, yogurt, lemon juice, soy sauce, and mustard and mix well. Use a spoon to fill each mushroom with the mixture, gently pressing it into the mushrooms. Bake for 20 minutes, until heated through and the tops begin to brown. Serve hot!