Preheat oven to 425 degrees F. Toss sweet potatoes with 2 tbsp olive oil on a baking sheet and season with salt and pepper. Arrange in a single layer and roast for 30 minutes turning once at 15 minutes.
In an oven proof 10-12in skillet, sauté the leaks on the stovetop in 1 tbsp olive oil until softened.
Whisk eggs, sour cream, ranch dip mix, ½ cup Parmesan, and 1 tbls parsley. Pour mixture over the leaks in warm skillet and stir. Layer sweet potatoes on top and sprinkle with remaining Parmesan cheese.
Bake until egg is set 15-20 minutes. Remove from oven and top with remaining chopped parsley. Serve warm.