Preheat your oven to 400°F (200°C)
Clean those mushrooms with a damp paper towel (never rinse them - they're like little sponges!)
Pop off the stems and finely chop them - we're not wasting those flavorful bits!
In a skillet over medium heat, sauté the chopped stems, garlic, and onion until golden
Mix the softened cream cheese, diced peppers, sautéed mushroom mixture, and half the Parmesan in a bowl
Stuff each mushroom cap generously - don't be shy!
Sprinkle remaining Parmesan on top
Bake for 18-23 minutes until golden brown and bubbly