For Fingerling potatoes, cut them in half lengthwise. Dice any other type of potato into ½-inch to ¾-inch cubes.
Pile the diced potatoes onto a rimmed baking sheet.
Drizzle with the Olive Oil. Sprinkle the salt, pepper, garlic, and rosemary over the pile of potatoes.
Using hands, or a pair of tongs, toss everything together.
Spread the potatoes in a single layer, trying to give a little room in between. Don't crowd them.
Bake the potatoes for 20 - 30 minutes until done. Use a fork to see if they are tender.
When done, remove the baking sheet from the oven and let the potatoes cool for a minute or two.
Serve.
Notes
If the potatoes stick to the baking sheet, use the back of the spatula in a scraping motion to remove them and preserve the crispy, golden brown goodness. For easier clean-up, you can use foil, but I have had better luck browning the potatoes by cooking them directly on the baking sheet.