Step 1

Evenly grease the cups of a 12-inch muffin tin with 1 tablespoon of the butter. Place in the refrigerator for at least an hour. (This isn't about preventing sticking as much as it is creating a crispy crust.)

Step 2

Heat your oven to 250℉. Arrange the bread pieces between the two half sheet pans and bake on the middle and lower third racks for 1 hour, switching the top pan to the lower rack and vice versa, after 30 minutes. The bread should be crisp and dried without browning. Transfer to your largest mixing bowl and set aside.

Step 3

Cook the sausage in a 12-inch cast iron skillet over medium-high heat, breaking up any chunks with the back of a wooden spoon and cook until the fat has rendered out, and the sausage is browned, about 6 minutes.

Step 4

Melt the remaining butter in the skillet then add the onion, celery, salt, pepper, sage, thyme, dry mustard, and rosemary and cook for 7 minutes, stirring frequently. Kill the heat, stir in the parsley and celery leaves and deposit the mixture into the bowl with the bread and mix well. Cool for 5 minutes.

Step 5

Combine the eggs and stock in a large measuring cup or bowl, then add to the bread bowl in two installments, allowing the first to be absorbed before adding the second.

Step 6

Retrieve the buttered muffin tin from the fridge and using an ice cream disher or large spoon, scoop about 5 1/2 ounces into your hand. Gently squeeze and shape into a ball shape and park in a muffin cup. Repeat with the remaining dressing until you've filled all the cups. If you have any leftover, evenly distribute amongst the cups and shape roughly into mounds.

Step 7

Tear a piece of aluminum foil 24-inches long and spray the dull side with no-stick spray. Cover the muffins tightly with the foil (lubed side down of course), and refrigerate overnight, or up to two days.

Step 8

When ready to bake, crank your oven to 350℉. When it reaches temp, remove the muffin tin from the fridge and place directly onto the middle rack of the oven, and bake for 20 minutes. Then, carefully remove the foil and bake 35 more minutes, until the dressing is deeply browned and crisp.

Step 9

Remove and cool for at least 15 minutes on a trivet or stovetop. To release, loosen the edges of the muffins with a small offset spatula or butter knife until the muffins release from the pan.