Heat the olive oil in a large skillet over medium heat. Add the squash, salt, and several grinds of pepper and sauté for 7 to 10 minutes, stirring occasionally, or until the squash is tender but still has a firm bite.

Turn off the heat and stir in the lemon juice, garlic, and parsley. Transfer to a serving dish and top with fresh basil and red pepper flakes, if desired.