Preheat oven to 425 degrees F. Lightly oil a 9×13 baking dish or coat with nonstick spray.In a small bowl, whisk together butter, garlic, lemon juice and lemon zest; set aside.Season tilapia with salt and pepper, to taste and place onto the prepared baking dish. Drizzle with butter mixture.Place into oven and bake until fish flakes easily with a fork, about 10-12 minutes.Serve immediately, garnished with parsley, if desired.