Preheat oven to 425°F and line a baking sheet with parchment paper.
Peel potatoes and slice into 1/4-inch thick rounds.
Cut heart shapes using a metal cookie cutter and place in cold water.
Bring a large pot of salted water to boil and add potato hearts.
Parboil for 5-7 minutes until almost tender but not falling apart.
Drain well and let sit in colander for 5 minutes to dry completely.
Mix olive oil, salt, pepper, garlic powder, and rosemary in a large bowl.
Toss potato hearts gently in the seasoned oil until evenly coated.
Spread in a single layer on baking sheet without touching.
Roast for 25-30 minutes, flipping halfway through, until golden and crispy.
