Step 1: Preheat and Prep
Preheat your oven to 425°F (220°C). This high temperature is crucial for achieving crispy, caramelized green beans. Position the oven rack in the center for even heat distribution. Line a large rimmed baking sheet with parchment paper if desired (makes cleanup easier but isn’t necessary).

Step 2: Trim the Green Beans
Wash the green beans thoroughly and pat completely dry with paper towels or a clean kitchen towel—excess moisture prevents proper browning. Trim off the stem ends (the tough part where they were attached to the plant). You can leave the tail end on; it’s perfectly edible and becomes crispy when roasted. Try to trim all beans to similar lengths for even cooking.

Step 3: Season the Green Beans
Place the trimmed, dry green beans in a large mixing bowl. Drizzle with olive oil, then add the minced garlic, salt, black pepper, and red pepper flakes if using. Toss everything together thoroughly with your hands or tongs, making sure every bean is well-coated with oil and seasonings. Really massage the garlic into the beans for maximum flavor.

Step 4: Arrange on Baking Sheet
Spread the seasoned green beans in a single layer on your prepared baking sheet. This is important—don’t pile them up or overcrowd! The beans should have space between them with minimal touching. Overcrowding creates steam instead of roasting, resulting in soft, not crispy beans. Use two pans if necessary.

Step 5: Roast
Place the baking sheet in the preheated oven and roast for 12-15 minutes, stirring once halfway through at the 7-minute mark. The beans are done when they’re crisp-tender with caramelized, slightly blistered spots and browned edges. They should still have a slight snap, not be mushy. Cooking time varies based on bean thickness—thinner French beans need less time (10-12 minutes), thicker beans need more (15-18 minutes).

Step 6: Add Cheese and Lemon
Remove the baking sheet from the oven. While the beans are still hot, immediately sprinkle the freshly grated Parmesan cheese over them and toss gently. The heat will melt the cheese slightly, helping it adhere to the beans. Squeeze fresh lemon juice over everything and toss again. The lemon brightens all the flavors beautifully. Add lemon zest if using.

Step 7: Serve
Transfer to a serving dish, garnish with fresh chopped parsley if desired, and serve immediately for the crispiest texture. These are best enjoyed hot from the oven!