Ingredients

• 4 large portobello mushroom caps, gills removed
• 4 teaspoons olive oil, divided
• 2 teaspoons balsamic vinegar
• 1/4 cup finely chopped shallots
• 2 teaspoons finely chopped garlic
• 1 teaspoon chopped fresh rosemary
• 1 can (19 ounces) cannellini beans, rinsed and drained
• 1/4 cup reduced-sodium chicken broth
• 1 ounce prosciutto, chopped
• 2 tablespoons finely chopped flat-leaf parsley
• 3/4 cup baby spinach
• 2 tablespoons panko breadcrumbs
• 2 tablespoons grated fresh Parmesan
• Olive oil cooking spray

Instructions

1. Heat oven to 450°. On a rimmed baking sheet lined with parchment paper, place caps top up. In a bowl, whisk 2 teaspoons oil and vinegar and season with salt and black pepper. Brush caps with oil mixture; reserve remaining mixture. Bake until tender, 8 minutes. In a skillet over medium heat, heat remaining 2 teaspoons oil. Cook shallots until soft, 2 minutes. Add garlic and rosemary; cook, 1 minute. Stir in beans and broth; season with black pepper. Remove from heat, stir in prosciutto and parsley and transfer to a bowl. In the same skillet over medium heat, cook spinach until wilted, 1 minute. Drain juice from caps and return to baking sheet, top down; brush with remaining oil mixture. Stuff caps with bean mixture and spinach. In a bowl, combine panko and Parmesan; divide among caps. Coat caps with cooking spray; bake until panko is golden, 10 minutes.