Preheat oven to 350 degrees F. Line a baking sheet with foil and set aside.
Use a damp paper towel to wipe the mushrooms clean from any debris. Gently pull the stems out of the caps and trim any woody parts away. Place mushroom caps stem-side up on the foil-lined baking sheet and set aside.
Finely chop the mushroom stems. Heat a pan over medium-high heat and add the avocado oil. Once hot add in the mushroom stems and diced bell pepper. Cook about 3 to 5 minutes, until most of the moisture is evaporated and veggies are tender. Add in garlic and cook until fragrant, about 30 seconds. Remove from the heat and let cool about 10 minutes.
In a medium bowl combine the cream cheese, parmesan cheese, Tastefully Simple® Rustic Herb Seasoning, parsley and cooked mushroom mixture. Use a sturdy spoon to mix completely and then scoop cream cheese mixture into mushroom caps.
Bake for 20 minutes, until cheese mixture is lightly browned and moisture begins to release at the bottom of the mushrooms. Garnish with extra parsley if desired. Enjoy right away.