• Preheat oven to 400 degrees F.
• Heat a large oven-safe skillet over medium heat. Add in the olive oil. Add the mushrooms stem side up and cook for 3 to 4 minutes. Flip and cook for 3 to 4 minutes more. Flip the mushrooms again and add in the vinegar and brown sugar, moving the mushrooms around to coat evenly. Cook for another minute, then turn off the heat.
• Scoop a half cup or so of mac and cheese (it can be right from the fridge) into each mushroom cap. Add a little extra grated cheese on top. Place in the oven until warm and the cheese is melted, about 10-15 minutes. Make the breadcrumbs while the mushrooms are cooking, then remove the mushrooms and cover them with the breadcrumbs, herbs and green onions. Serve immediately!

breadcrumbs

• Add butter to a small saucepan over medium heat and whisk constantly while it bubbles. The minute brown bits begin to form on the bottom of the pan, remove from heat and whisk for an additional 30 seconds. (for more step by step photos of browning butter, click here) Let butter stand for 2 minutes, then add in minced garlic and whisk. Add in panko and stir well to coat and combine. Set aside.