Preheat your oven to 425°F. Line a large baking sheet with parchment paper for easy cleanup.
In a large bowl, combine the halved baby potatoes, olive oil, salt, black pepper, garlic powder, and rosemary. Toss until the potatoes are evenly coated.
Spread the potatoes in a single layer on the prepared baking sheet, cut side down. Roast in the preheated oven for 25-30 minutes, or until golden brown and crispy, flipping halfway through for even cooking.
While the potatoes are roasting, prepare the salted lemon mixture. In a small bowl, combine the lemon zest, lemon juice, and capers. Set aside.
Once the potatoes are done, remove them from the oven and immediately drizzle the salted lemon mixture over the hot potatoes. Toss gently to combine.
Garnish with chopped fresh parsley before serving.