Spinach and Cheese Stuffed Portobello Mushrooms

Preheat your oven to 375°F (190°C).
Remove the stems and scrape out the gills of the Portobello mushrooms.
Brush the mushroom caps with olive oil and balsamic vinegar (if using). Season with salt and pepper.
Place the mushrooms, cap side down, on a baking sheet lined with parchment paper.
Prepare the Filling:

In a skillet, heat 1 tablespoon of olive oil or butter over medium heat.
Add the minced garlic and sauté for 1-2 minutes until fragrant.
Add the chopped spinach and cook until wilted, about 2-3 minutes.
Remove from heat and let it cool slightly.
In a bowl, combine the ricotta cheese, shredded mozzarella, spinach mixture, and a pinch of nutmeg (if using). Stir until well combined.
Stuff the Mushrooms:

Spoon the spinach and cheese mixture into each mushroom cap, pressing gently to pack the filling in.
Bake the Mushrooms:

Place the stuffed mushrooms back on the baking sheet and bake in the preheated oven for 20-25 minutes, or until the mushrooms are tender and the filling is golden and bubbly.
Serve:

Serve hot as an appetizer, side dish, or light main course. Garnish with additional fresh herbs or grated Parmesan if desired.
Serving and Storage Tips: