1) Preheat oven to 425 degrees F. Use a paring knife to hollow out mushrooms.
2) Chop chems roughly from mushrooms and measure out about 1/3-1/2 cup.
3) In a large skillet, melt butter over medium heat and add chopped stems, onions, and garlic. Add a pinch or two of salt and let that start to cook down for about 4 minutes. After that add your crab, Parm, and 3/4 cup bread crumbs.
4) Once filling is cooked, spoon filling back into mushrooms. YOu can really stuff them full. in your filling. Dust mushrooms with extra breadcrumbs or panko.
5) Bake for 15-20 minutes. Then cool for 5 minutes and serve them up!