Preheat oven to 425 degrees F. Toss sweet potatoes with 2 tablespoons olive oil on rimmed baking sheet and season with salt and pepper. Arrange in single layer and roast, flipping halfway through, until golden and tender, 25 to 30 minutes. Reduce oven to 350 degrees F.
Heat 1 tablespoon oil in non-stick oven-proof skillet over medium-high heat. Add leeks and cook, stirring often, until softened, 6 to 8 minutes. Transfer to large bowl. Whisk in eggs, sour cream, Hidden Valley® Original Ranch® Dips Mix, ½ cup Parmesan, and 1 tablespoon fresh parsley.
Add remaining tablespoon oil to skillet and pour in egg mixture. Add sweet potatoes in even layer and cook, undisturbed, until egg starts to set around edges, about 5 minutes. Sprinkle top with remaining ¼ cup Parmesan and transfer skillet to oven. Bake until egg is set, 15 to 20 minutes. Sprinkle with remaining tablespoon parsley before serving.