Start by cleaning the cremini mushrooms with a damp paper towel. This helps remove any dirt without soaking them in water. Once clean, quarter the mushrooms into bite-sized pieces.
In a small bowl, combine the balsamic vinegar, brown sugar, and water. Stir until the sugar is dissolved and set aside. This mixture will provide a wonderful glaze for the mushrooms.
In a large skillet, heat 1 tablespoon of unsalted butter and 2 tablespoons of extra virgin olive oil over medium heat. Once the butter has melted and starts to bubble, you’re ready to add the mushrooms.
Add the quartered mushrooms to the skillet, sprinkling them with kosher salt. Sauté for about 5-7 minutes, stirring occasionally until they soften and begin to brown.
Once the mushrooms are nicely browned, add the minced garlic and sauté for another minute until fragrant. Then, pour the balsamic mixture into the skillet and stir well to coat the mushrooms.
Add the remaining tablespoon of butter to the skillet. This will enrich the sauce and give the mushrooms a lovely sheen. Cook for an additional 2-3 minutes, allowing the sauce to thicken slightly.
Taste the mushrooms and adjust seasoning with freshly ground black pepper if desired. Remove from heat and serve warm.