Preheat oven to 325 degrees. Spray cooking spray into muffin tin and line each tin with parchment muffin cups.
In large skillet, heat olive oil to high heat. Break up sausage in pan, then turn to medium heat just before fully cooked. Add the onion, garlic, and celery and cook all until sausage is done and onions are translucent.
Add seasoning packet that came with Stuffing mix (or not, if you bought the kind that’s pre-seasoned), and add the chicken broth. Let cook for 3 - 5 minutes until simmering, and add thyme and sage just before removing from heat.
Spoon the mix into muffin tins, filling just 2/3 full. Add an even amount of cheddar atop each muffin, and then top it off with a small spoonful of stuffing. Bake for 25 - 30 minutes, until stuffing is set and cheese is melty.