– extra virgin olive oil
– finely chopped yellow onion
– chopped fresh basil
– finely chopped fresh rosemary
– large cloves of garlic
– cooked shrimp
– fresh breadcrumbs made from French bread
– grated Parmesan cheese
– mayonnaise
– Portobello mushrooms, stems and dark gills removed with a spoon
– salt and pepper to taste
8. Fill the mushrooms, making sure to press the filling in tightly and mound. Make-ahead: at this point the mushrooms can be stored, covered, in the refrigerator for up to 6 hours.