Preheat oven to 400F. Line a baking sheet with parchment paper.
Combine the garlic powder, salt, pepper, onion powder and red pepper flakes in a small bowl. Mix until combined.
Chop the ends of the asparagus and chop the asparagus into small pieces, about 1.5 to 2 inches long. Cut the ends of the brussels sprouts.
Add the asparagus and brussels sprouts to a bowl. Pour the spices over the top. Mix well. Add the olive oil. Mix well.
Spread the veggies evenly on a pan. Veggies should lay flat and should not be stacked. Squeeze lemon juice over the top.
Bake in the oven, flipping with tongs or a spatula halfway through. Garnish with parmesan cheese once cooked.
Notes
Tips:
Pat the veggies dry with a kitchen towel before tossing them in olive oil and seasoning. Moisture on the Brussels sprouts or asparagus can hinder the crisping process
Use High Heat: Be sure to roast at a high temp of 400F. This promotes caramelization and crispiness. Don't be afraid to let the edges get brown and crispy for maximum flavor.
Single Layer: Spread the veggies out in a single layer on the baking sheet. Crowding can lead to steaming instead of roasting, resulting in softer, less crispy sprouts and asparagus.
Check for Doneness: Test a Brussels sprout by piercing it with a fork to ensure it's tender and crispy on the outside. Adjust the roasting time if needed to achieve the desired texture.