Preheat oven to 400º
Prep vegetables, and lay them out on a large baking pan, in one even layer. (You can also prep them in a large mixing bowl if that's easier)
If you choose to use butter, mix your melted butter and olive oil in a small bowl.
Pour olive oil (or olive oil/butter mixture) over the sprouts, and season generously. Feel free to add more of any of the seasonings, as you see fit. I add a lot, but am sparing with the red pepper flakes.
Make sure the sprouts are evenly coated in olive oil and seasonings, and evenly distributed across your baking pan.
Roast Brussels sprouts in the oven for 25-30 minutes, or until brown and crispy. Flip them at the halfway mark, and start monitoring them around 20-25 minutes to make sure they don't overcook.
Sprouts will be fork-tender and browned when finished. Serve alongside your favorite protein, for a well-rounded meal.