Start by cleaning the baby bella mushrooms with a damp cloth and slice them into halves or quarters. Mince the garlic and onion, and chop the parsley and rosemary.
In a large skillet, heat 1 tablespoon of butter and 1 tablespoon of olive oil over medium heat until the butter melts completely.
Add the minced onions to the skillet and sauté for about 3-4 minutes until translucent. Stir in the minced garlic and cook for another minute until fragrant.
Add the sliced baby bella mushrooms to the skillet and sauté for 5-7 minutes, stirring occasionally, until golden brown and tender.
In a small bowl, mix the balsamic vinegar, soy sauce, and brown sugar. Pour this mixture over the mushrooms and stir well. Allow it to simmer for 3-5 minutes.
Stir in the minced parsley and rosemary. Taste and adjust seasoning if necessary, adding more brown sugar for sweetness if needed.
Remove from heat and transfer the Garlic Balsamic Mushrooms to a serving dish. Enjoy them warm for the best flavor experience!