Preheat the oven to 375 degrees. bring a large pot of salted water to a boil and cook the brussel sprouts until the leaves are vibrant green.
Drain the brussel sprouts and immediately transfer to an ice bath in a large mixing bowl, let chill for about 5 minutes.
Once the brussel sprouts are chilled, put into an oven safe cast iron skillet or pan and set aside.
Over medium heat in a separate cast iron skillet, melt the butter and cook the following ingredients: shallot, garlic, thyme, and pepper. let cook until the shallots are softened, stirring occasionally.
Stir in the heavy cream, sour cream, nutmeg, and two tsp of salt.
Remove the skillet from the heat and add the parmesan and mozzarella cheese, stir until smooth.
Pour the cheese mixture over the brussel sprouts and toss to coat completely. top with extra mozzarella cheese.
Bake the creamed brussel sprouts uncovered for about 30 minutes (until golden brown).
Top with fresh chives & enjoy!