Optional for serving: Freshly squeezed lemon juice or freshly grated Parmesan
Position racks in the upper and lower thirds of your oven. Line a large rimmed baking sheet with parchment paper and place it on the lower rack. Preheat the oven to 450 degrees F with the sheet pan in it. You want there to be plenty of room for the sprouts, so if you think they will be crowded, use two sheet pans and bake them on the upper and lower racks instead.
Once the oven is heated, remove the sheet pan from the oven and carefully pour the Brussels sprouts into the center. With a spatula, spread them out, then return the pan to the lower rack. Bake for 15 minutes.
Remove the pan from the oven. Drizzle the sprouts with the oil and sprinkle with salt and pepper. With a spoon or spatula, stir to coat. Return the pan to the lower rack (if you are using two pans, switch their positions on the upper and lower racks). Continue baking for 10 to 15 additional minutes, until the sprouts are browned on the outside and tender on the inside. Squeeze lemon juice over the top and sprinkle with Parmesan. Enjoy!
Frozen Brussels sprouts will simply not be as crisp as if you roasted fresh Brussels sprouts, but they are a zero-prep, affordable option! If texture is very important to you, I recommend my oven Roasted Brussels Sprouts or Sautéed Brussels Sprouts.
TO STORE: Place leftover Brussels sprouts in an airtight storage container in the refrigerator for up to 4 days.
TO REHEAT: Rewarm leftovers on a baking sheet in the oven at 350 degrees F until hot. You can also reheat the sprouts in the microwave.