1. Preheat oven to 350°F and remove mushroom stems from mushroom caps.
2. Finely chop stems and set them aside.
3. In a non-stick skillet, heat margarine or olive oil and add seasonings, chopped mushroom stems, and onions for 5 to 10 minutes, until tender.
4. Add crab meat and cook for another 2 minutes, then remove from heat.
5. Pulse the bread slices together in a food processor or high-speed blender to make the bread crumbs.
6. Then, stir the bread crumbs and cheese into the warm seasoned crab meat.
7. Divide the stuffing amongst the cap and place them on a parchment paper-lined baking sheet.
8. Bake mushroom caps in the hot oven for 12 to 15 minutes, until golden brown.
