STUFFED PORTOBELLO MUSHROOMS

Steps:

• Preheat the oven to 450°F. Set the mushrooms gill side up on a rimmed baking sheet. Drizzle with the oil and vinegar and season with salt and pepper. Bake for 15 minutes.
• Meanwhile, coat a large nonstick skillet with cooking spray; place over medium heat. Add the leek; cook for 5 minutes, stirring. Add the spinach a handful at a time, stirring constantly, until it cooks down. Stir in the beans and salt and pepper to taste; cook for 1 minute to combine the flavors.
• Fill the mushroom cavities with the spinach mixture. Sprinkle with the cheese. Bake for 10 minutes, until the mushrooms are warmed through and the cheese is melted. Serve.