Start by setting your air fryer to 400°F. If your model requires preheating, let it run for about 3-4 minutes. This matters because you want the basket and heating element at temperature when your potatoes arrive, ensuring immediate crisping on the outside. While the air fryer heats, wash your potatoes thoroughly under cool water, using a vegetable brush if you have one. Pat them completely dry with a clean kitchen towel—excess moisture is the enemy of crispiness. You don't need to peel them; the skin provides nutrients, texture contrast, and honestly, more personality on the plate.

Using a sharp chef's knife (this is worth investing in if you haven't already), cut each potato into cubes roughly ½ to ¾ inch in size. Consistency matters here. Pieces of similar size cook at the same rate, preventing some from turning into mush while others remain firm. I typically cut each potato into quarters lengthwise first, then slice those into sticks, then cut across to create cubes. The reason I'm specific about size: smaller pieces cook faster but can become too crispy; larger pieces take longer and may not get as golden. The ½ to ¾ inch range gives you that perfect window where the outside gets golden and crispy while the inside remains creamy and tender.

Place your cut potatoes in a mixing bowl and drizzle with the olive oil. Toss thoroughly, using your hands or two spoons to ensure every piece gets coated. This should take about 2-3 minutes of attention. Each cube needs a light layer of oil; this is what creates the crispy exterior. Once coated, add your garlic powder, paprika, dried rosemary, salt, and pepper. If using the lemon, add both the juice and the zest now. Toss again until the spices are distributed evenly. This is where the magic starts—you're not just seasoning potatoes; you're creating layers of flavor that will develop and deepen as they cook.

If your air fryer basket is generous in size, you may fit all the potatoes in one batch. More likely, you'll need to work in two batches—and that's completely fine. Arrange them in a single layer, avoiding stacking. If you have an air fryer liner (perforated or mesh), use it to prevent any pieces from falling through the basket. Set the timer for 10 minutes. They won't be done yet, but this first phase cooks them through and begins the crisping process.

At the 10-minute mark, open the basket carefully—steam will release. Give the potatoes a good shake, stirring them around so the ones on the edges move to the center and vice versa. This ensures even cooking and browning. If using Parmesan cheese, do NOT add it yet. Return the basket to the air fryer and cook for another 5-10 minutes. Begin checking at the 5-minute mark. You're looking for the exterior to be golden brown with some darker spots, and a quick taste test should reveal a tender, almost creamy interior.

In the final 5 minutes of cooking, if you're using the Parmesan cheese, add it now. Remove the basket, sprinkle the cheese evenly, and return it to finish cooking. The residual heat will melt it into the hot potatoes, creating pockets of savory richness. When they're done, transfer them immediately to a serving dish. They'll continue to firm up slightly as they cool. If you prefer extra crispiness, add 1-2 more minutes, but watch carefully as they can go from perfectly crispy to burnt quickly at this stage.