Preheat your oven to 375°F. Grease a 12-cup muffin tin with cooking spray.
Melt butter in a medium skillet over medium heat. Add sausage and cook until browned, breaking up the meat with a wooden spoon. Add the onion and celery, and continue to sauté until the vegetables have softened, which should take about 5 minutes. Stir in garlic, thyme, sage, and rosemary. Season with salt and pepper to your taste. Remove from heat and let it cool slightly.
In a large bowl, mix together bread cubes, sausage mixture, and chicken broth. Check for seasonings and add salt and pepper if needed. Then, stir in the egg.
Divide the stuffing mixture evenly between the muffin tin cups. Bake until warmed through and golden on top, which should take about 25 to 30 minutes.
Enjoy the crispy goodness of these Stuffin’ Muffins at your Thanksgiving table!