Cheese & Spinach Stuffed Portobellos

I made this in May, so it doesn't count towards my no-oven August challenge.  We have finally figured out that we love portobellos! 

Cheese & Spinach-Stuffed Portobellos

Adapted from EatingWell:  March/April 2009

4 large portobello mushroom caps

1/4 teaspoon salt

1/4 teaspoon freshly ground pepper, divided

1 cup part-skim ricotta cheese

1 cup chopped or torn fresh spinach

1/2 cup finely shredded Parmesan cheese, divided

1/2 teaspoon Italian seasoning (I used 21 Seasoning Salute from Trader Joes)

3/4 cup prepared marinara sauce

Preheat oven to 450°F. Coat a rimmed baking sheet with cooking spray.

Place mushroom caps, gill-side up, on the prepared pan. Sprinkle with salt and 1/8 teaspoon pepper. Roast until tender, 20 to 25 minutes.

Meanwhile, mash ricotta, spinach, 1/4 cup Parmesan, seasoning and the remaining 1/8 teaspoon pepper in a medium bowl. Place marinara sauce in a small bowl, cover and microwave on High until hot, 30 seconds to 1 1/2 minutes.

When the mushrooms are tender, carefully pour out any liquid accumulated in the caps. Return the caps to the pan gill-side up. Spread 1 tablespoon marinara into each cap; cover the remaining sauce to keep warm. Mound a generous 1/3 cup ricotta filling into each cap and sprinkle with the remaining 1/4 cup Parmesan. Bake until hot, about 10 minutes. Serve with the remaining marinara sauce.