Preheat the oven to 450.
Heat the olive oil and/or butter in a large skillet.
Add the mushroom caps and stir to cover.
Heat slightly to soften the caps.
Remove to an oven proof pan or casserole dish, set aside.
Add the crab to the skillet, and season with the garlic powder, Old Bay, Worcestershire Sauce, salt and pepper. Add more butter or olive oil if needed.
Stir in the bread crumbs, Parmesan cheese and lemon juice.
Fill the mushroom caps with the crab mixture.
Place in the oven for 5 to 8 minutes until heated through and the bread crumbs begin to brown.