Preheat the oven to 425˚F. Place the butter in a 9 x 13-inch baking dish and set in the oven for 5 minutes, until the butter is melted.
Remove the dish from the oven, stir in the spices and parmigiano reggiano until well combined and they form a paste. Spread with a spatula to coat the bottom of the pan with the paste.
Place the halved brussel sprouts cut side down in the baking dish. Bake until golden brown and crispy, about 35 minutes.
Remove the brussel sprouts from the pan and add to a serving platter with aioli, if desired.
Notes
Nutrition label does not include aioli.You can store the leftover Brussel sprouts in an airtight container and refrigerate them. When you're ready to eat them again, you have a few options for reheating. You can warm them up on the stovetop or use the microwave, or for to get the same crispness to them you can reheat in a hot oven or air fryer at around 400 degrees until they are heated through.Make sure the oven is preheated before roasting to make sure they cook evenly and crisp up.