Preheat the oven to 425° F. Add the potatoes to a rimmed sheet pan. Add the butter, 1 teaspoon olive oil, salt, and pepper. Toss. Roast for about 25 minutes, until colorful and starting to crisp.
Meanwhile, combine the salt, black pepper, parmesan, parsley, garlic, and onion in a bowl.
After the potatoes have been in for 25 minutes, take them out of the oven. Drizzle the remaining ½ teaspoon olive oil, then sprinkle with the seasoning. Gently toss to coat the potatoes. Roast for another 6 or so minutes until they’re as crispy as you like—I like a sturdy crust and fluffy interior. Cool before serving atop salad, but eat day-of.
Emma is the food editor at Food52. Before this, she worked a lot of odd jobs, all at the same time. Think: stir-frying noodles "on the fly," baking dozens of pastries at 3 a.m., reviewing restaurants, and writing articles about everything from how to use leftover mashed potatoes to the history of pies in North Carolina. Now she lives in New Jersey with her husband and their cat, Butter. Stay tuned every Tuesday for Emma's cooking column, Big Little Recipes, all about big flavor and little ingredient lists. And see what she's up to on Instagram at @emmalaperruque.