Prep the Sprouts: Rinse the brussels sprouts under cold water and pat them completely dry with paper towels. Trim the stem ends and remove any yellowed or damaged outer leaves, then halve each sprout lengthwise so the flat side can make contact with the cooking surface.
Heat Your Pan: Place a large skillet over medium-high heat and add the olive oil, allowing it to shimmer for about 1 minute until it's hot but not smoking.
Cook Cut-Side Down: Carefully arrange the brussels sprout halves in a single layer with the flat side facing down, and let them sear without stirring for 5-7 minutes until the cut side turns deep golden brown and slightly caramelized.
Finish Cooking: Shake the pan to flip the sprouts, then reduce heat to medium and cook for another 5-8 minutes, stirring occasionally, until the outer leaves are crispy and the flesh is tender when pierced with a fork.
Season and Smash: Remove from heat, sprinkle with garlic powder, salt, and pepper, then gently press some of the larger sprouts with the back of a spoon to break them up slightly while keeping them mostly intact. Top with parmesan cheese and serve immediately.