Preheat oven to 425 degrees F. Scrub baby potatoes and pat completely dry. Halve any potatoes larger than 1 inch so they cook evenly. Wet potatoes steam instead of roast, so drying is crucial.

In a large bowl, toss potatoes with olive oil, minced garlic, chopped rosemary, kosher salt, and black pepper until evenly coated. The potatoes should look glossy but not swimming in oil.

Spread potatoes in a single layer on a large rimmed baking sheet, cut side down where possible. Crowding leads to steaming, so use two sheets if needed. Give them space.

Roast for 20 minutes without moving them. Flip with a spatula and continue roasting 12 to 15 minutes until deeply golden and crisp on the outside, tender when pierced with a knife. The cut sides should have a deep brown crust.

Transfer to a serving bowl, sprinkle with fresh parsley and flaky sea salt if desired. Serve immediately while the edges stay crisp.