Preheat oven to 400 degrees F. Spray a baking sheet with nonstick spray.
Trim the ends off of the brussels sprouts. If you have a mixture of large and small brussels sprouts, slice the larger ones in half or quarters. Keep the small brussels sprouts intact.If using all small brussels sprouts, slice in half or keep whole. I prefer mine sliced in half if they are not too small to get a nice crisp edge when they roast cut-side down.
To a large bowl, combine the melted butter, olive oil, salt, pepper, garlic powder, and onion powder. Stir to fully combine. Add in the brussels sprouts and gently toss to thoroughly combine with the butter mixture.
Next, add in the panko and parmesan cheese. Toss gently to combine.
Transfer the brussels sprouts to the prepared baking sheet, making sure to create a single, spaced out layer. Arrange any sliced sprouts cut-side down.If you have any leftover breadcrumb/cheese mixture, simply sprinkle overtop of the sprouts and press down slightly to help it stick.
Bake 15-20 minutes or until sprouts are fork-tender and lightly browned. Check at 15 minutes. Roasting time will vary based on the size of the sprouts. It's important to keep an eye on them to avoid burning.
Best served right out of the oven. Garnish with additional parmesan cheese, if desired.
BAKE TIME: Please keep in mind that roasting time will vary depending on how large OR small the brussels sprouts are. The bake time listed above (15-20 minutes) is based on 1.5 lbs of smaller brussels sprouts. Check at 18-20 minutes for larger brussels sprouts and go from there. The sprouts should be lightly browned, crisp, and fork-tender when done. It's very easy to overcook them, so keep an eye on them.MAKE AHEAD? I do not recommend making these ahead of time. They are best served freshly roasted out of the oven. Leftovers will soften as they sit and will be difficult to crisp up again without overcooking them.