In a small dish, whisk together the balsamic vinegar, brown sugar, and 1 tablespoon of water. This mixture will become the sauce that enhances our mushrooms. Make sure it’s well combined so that the flavors meld perfectly.
Next, grab a large skillet and heat 1 tablespoon of unsalted butter along with 2 tablespoons of extra virgin olive oil over medium-high heat. The combination of butter and oil will give your mushrooms a rich, golden color. Wait for the butter to melt and bubble before you proceed.
Once the butter is melted, it’s time to add the quartered cremini mushrooms and Kosher salt. Stir immediately with a wooden spoon to ensure that all the mushrooms are coated with the butter and salt. This step is crucial for flavor absorption.
Allow the mushrooms to cook undisturbed for 2 minutes. This helps them develop a lovely golden crust. Afterward, give them a gentle stir. You might notice that the pan appears dry, but that’s normal. Keep the heat at medium-high.
Continue to cook the mushrooms, stirring infrequently, until they are shrunken, glistening, and some sides have developed a deep orange-brown color, about 6 to 7 minutes more. The bottom of the pan will be brown, which adds to the flavor.
Once the mushrooms reach that beautiful color, turn the heat down to low. Add the minced garlic and the remaining 1 tablespoon of butter. Stir until the butter melts and the garlic becomes fragrant, which should take about 15 to 20 seconds. This will infuse the dish with a wonderful aroma.
Carefully pour in the balsamic mixture you whisked earlier. Cook while stirring until the liquid reduces to a glazey consistency that coats the mushrooms, about 15 to 20 seconds. You’ll know it’s ready when the mushrooms glisten with flavor.
Season with a few grinds of freshly ground black pepper. This will enhance the dish and add a subtle kick.
Transfer the mushrooms to a serving dish, making sure to scrape the pan with a rubber spatula to get all of that garlicky sauce. Let them sit for a few minutes to allow the flavors to marry before serving warm.