Preheat your oven to 425°F (220°C). Line a large baking sheet with parchment paper or foil for easy cleanup.
Wash and trim the ends off your green beans. Pat them dry with a towel
In a large bowl (or right on the baking sheet), toss the green beans with olive oil, garlic, salt, and pepper. Make sure they’re evenly coated.
Sprinkle the Parmesan over the top and toss again so the cheese sticks to the oil-coated beans.
Spread the green beans out in a single layer on the baking sheet. Don’t overcrowd — give them space to roast, not steam.
Roast for 15 to 18 minutes, or until the green beans are tender with crispy, golden edges. The Parmesan will melt and form little toasty bits — aka the best part.
If you like your beans extra crisp, leave them in for a minute or two longer, watching carefully so the cheese doesn’t burn.