Preheat your oven to 400°F and line a large baking sheet with parchment paper or foil. While the oven heats, trim the stem ends from the green beans and pat them completely dry with paper towels—this is crucial for achieving that crispy, roasted exterior rather than steamed beans. In a large bowl, toss the dried beans with olive oil, minced garlic, onion powder, salt, and pepper until every bean is evenly coated. I like to use a large spoon to toss thoroughly so the seasonings are distributed uniformly.

Spread the seasoned green beans in a single layer on your prepared baking sheet, allowing them to lie flat so they roast evenly rather than pile up. Immediately sprinkle the freshly grated parmesan cheese evenly over the beans—adding it at the start of roasting allows the cheese to melt into the beans and create a light, golden crust. Roast in the preheated 400°F oven for about 20 minutes, stirring halfway through cooking to ensure even browning and cheese distribution. The beans should be tender-crisp and the cheese should be golden when ready.

Remove the roasted beans from the oven and immediately drizzle with fresh lemon juice, then toss gently to combine. The lemon juice will add a bright, fresh note that balances the richness of the parmesan. Sprinkle the chopped fresh parsley over the top for a pop of color and herbaceous flavor. Serve immediately while the beans are still warm and crispy.