Heat a large nonstick pan over medium heat. Place a tablespoon of oil into the pan. Add the green beans, carefully (remember they are frozen). Cook until tender and cooked through. *Make sure not to overcook the beans.
Remove the green beans and transfer them to a medium-sized bowl. Cover with foil to keep them warm.
Place the remaining oil into the skillet. Add the garlic and cook until golden brown. Keep a close eye so that the garlic does not burn. Add the red pepper flakes and cook for 30 seconds more.
Pour the garlic olive oil over the green beans and toss to coat. Add parsley, lemon juice, if using, and ¼ of the Parmesan cheese. Place onto the desired serving dish and garnish with the remaining Parmesan. Serve immediately.