Blanch the green beans. Fill a saute pan or a frying pan with about 1/2 inch of salted water and bring it to a boil. Add the green beans to the boiling water, cover, and cook until they are tender to the bite, about 3 to 5 minutes, depending on how crisp you like your green beans.
Cool the beans. Drain the beans and wash under cold water until completely cooled.
Infuse the butter. Meanwhile, melt the butter in a nonstick frying pan over medium heat. Add the lemon zest and continue to cook and stir for about 1 minute.
Combine. Put the green beans back in the pan and pour the lemon butter over them; add lemon juice, salt, and pepper, and toss to combine. Taste and adjust.
Finish and serve. Transfer the lemon butter green beans to a serving plate. Garnish with parmesan cheese and serve.