There are a couple of summer vegetables adding pizazz to this dish, but the warmth from the oven and each cheesy bite makes this a cold weather winner. This dish is vegetarian, gluten-free and can even be made with meat!
4 large portobello mushrooms
1/2 c red onion, finely diced
1 tbsp crushed garlic
1 large carrot, roughly shredded
1 zucchini, roughly shredded
1 small bell pepper, diced
2 tbsp lemon juice
2 c packed baby spinach leaves
1 tsp sea salt
1/2 tsp black pepper
1/2 c grated Parmesan cheese
1/2 c ground oats*
1 c Italian-style shredded cheese
Preheat oven to 400 degrees and place a sheet of aluminum foil on a shallow-rimmed baking sheet. Wipe mushrooms clean with a damp paper towel and remove stems**, if necessary. Set aside. In a large skillet, heat 1 tbsp extra-virgin olive oil and 1 tbsp butter over medium-high heat. Add onion and cook for one minute; add garlic and stir until fragrant and onions are soft (about 1 minute). Add carrot, zucchini, and bell pepper and cook, stirring occasionally, for about 4 minutes over medium heat. Stir in lemon juice, salt and pepper. Dump spinach leaves on top of vegetable mixture and cover; remove from heat after 2 minutes or when spinach is wilted (vegetable mixture will be very wet). Stir in ground oats and 1/4 c Parmesan. Place mushrooms on prepared baking dish and place a generous helping of cheese on each (~1/4 c). Top each mushroom with vegetable mixture, dividing it up among the four mushrooms. Bake 12 minutes and top with remaining Parmesan. Bake another 3-5 minutes or until cheese is browned on top. Serve immediately.
Optional meat add-in: Place a piece of prosciutto or ham on top of cheese before putting vegetables on top. You can also fill the mushroom cap with ground sausage or hamburger before adding the cheese. Reduce salt in the recipe if using ham or sausage.
*I prefer the texture and flavor of ground oats to bread crumbs. I just coarsely grind them in my blender or food processor in large batches and keep them in a container next to my flour and sugar.
**If desired, you can dice the stems of the mushrooms and add them to the onion with the other vegetables.