Heat the olive oil in a large skillet over medium-high heat. Add the zucchini in a single layer (as much as possible), and cook without stirring for 3 to 4 minutes, or until browned underneath.

Stir in the garlic, salt, and several grinds of pepper. Cook, stirring occasionally, for 5 to 8 minutes, or until the zucchini is tender and browned in places.

Squeeze lemon juice on top and season with salt and pepper to taste. Sprinkle with red pepper flakes, if using. Garnish with parsley and serve with Parmesan, if desired.