- 1/4 cup chopped fresh basil
- 3 large garlic cloves, chopped
- 1/2 teaspoon chopped fresh rosemary
- 6 ounces cooked bay shrimp
- 2/3 cup fresh breadcrumbs made from crustless French bread
- 1/2 cup grated Parmesan cheese
- 8 2- to 2 1/2-inch portobello mushrooms, dark gills removed
Heat oil in heavy large skillet over medium-high heat. Add onion, basil, garlic, and rosemary. Sauté until onion softens, about 5 minutes. Transfer to medium bowl; mix in shrimp, breadcrumbs, cheese, and mayonnaise. Season filling to taste with salt and pepper. Arrange mushrooms, rounded side down, on oiled baking sheet. Mound shrimp filling in mushrooms, pressing filling to compact slightly. DO AHEAD Can be made 6 hours ahead. Cover and refrigerate.
Preheat oven to 350°F. Bake mushrooms until tender and filling begins to brown, about 35 minutes. Serve hot.