Preheat oven to 400°F. Line a rimmed baking sheet with foil or parchment paper for easy cleanup. In a large bowl, toss together the potatoes, olive oil, garlic, rosemary and salt.
Spread the potatoes in a single layer on the prepared baking sheet.
Roast the potatoes for about 40-50 minutes, or until they’re golden brown and crispy on the outside and fork tender. Stir the potatoes every 15-20 minutes so that they brown evenly. The total roasting time will varydepending on the size of your potato pieces and on how crispy you like them. They might be done in as little as 40 minutes, or they might require up to 1 hour. Just keep an eye on them and pull them out when they're just how you like them! Season with additional salt and pepper, to taste.
Notes
Make sure that your potatoes are very dry before tossing them with the other ingredients. You don't want extra moisture on the potatoes or they will steam in the oven and won't be nearly as crispy.
Cut the potatoes into uniform size pieces so that they cook evenly.