Preheat oven to 400 degrees F. Lightly oil a baking sheet or coat with nonstick spray.
Place potatoes in a single layer onto the prepared baking sheet. Add olive oil, lemon juice, garlic and rosemary; season with salt and pepper, to taste. Gently toss to combine.
Place into oven and bake for 25-30 minutes, or until golden brown and crisp. Stir in butter until melted, about 1 minute.
Serve immediately, garnished with lemon zest, parsley and rosemary, if desired.