Smashed Potatoes with Arugula Pesto

Preheat oven to 400°. Place potatoes in a large pot; add water to cover by 1 inch. Stir in 1 tablespoon salt. Bring to a boil; reduce heat. Simmer, uncovered, until potatoes are tender, 20 to 30 minutes; drain.

Meanwhile, for pesto, in a food processor, combine arugula, walnuts, Parmesan, garlic and 1/4 teaspoon salt. Process to a paste. Add olive oil and balsamic vinegar. Process until smooth.

Generously oil a large rimmed baking sheet. Place potatoes on baking sheet; press with a potato masher or glass to 1/2- to 3/4-inch thickness. Drizzle with 2 tablespoons olive oil; sprinkle with 1/2 teaspoon salt and the black pepper. Bake until edges are golden, about 25 minutes. Spoon pesto over potatoes.