Melt butter in a heavy-bottomed pan over medium-high heat. Add mushrooms and thyme. Sauté for 5 to 7 minutes or until they’re fully coated with butter and start to crackle and pop. Add garlic and cook for another 2 to 3 minutes, stirring frequently, making sure not to burn the garlic. Once mushrooms take on a golden browned color but are still nicely soft and juicy, remove pan from heat. Season to taste with salt and pepper. Serve right away between two slices of white sandwich bread.