Set an oven rack in the middle position and preheat the oven to 450°F. Line a rimmed baking sheet with heavy-duty aluminum foil or parchment paper.
In a small dry skillet over medium heat, toast the pine nuts until golden. Watch carefully and stir frequently as they can burn quickly! Immediately transfer to small bowl. Set aside.
Put the green beans in a large bowl. Add the sliced garlic, olive oil, 1 teaspoon of the lemon zest, kosher salt, pepper and sugar and toss well. Transfer the mixture to prepared baking sheet.
Roast the beans and garlic for 15 minutes. Stir with a spatula to promote even cooking, then continue roasting until the beans are tender throughout, about 10 minutes more. The beans should be fully cooked, lightly browned but not shriveled.
Add lemon juice, Parmigiano-Reggiano, remaining 2 teaspoons lemon zest and pine nuts to beans and toss well. Taste and adjust seasoning with salt, pepper and lemon juice if necessary. Serve hot or at room temperature.
