1/2 large onion, sliced lengthwise 1/4 inch thick (1 cup)
2 1/2 tablespoons extra-virgin olive oil, divided
1/4 teaspoon Spanish smoked paprika
2 pounds Swiss chard, center ribs discarded and leaves coarsely chopped
1/2 cup golden raisins
1/2 cup water
1/4 cup coarsely chopped almonds with skins
Cook onion with 1/4 teaspoon salt in 2 tablespoons oil in a 5- to 6-quart heavy pot over medium heat, stirring, until softened. Sprinkle with paprika and cook, stirring, 1 minute. Add chard in batches, stirring frequently, until wilted, then add raisins and water. Cook, covered, stirring occasionally, until chard is tender, about 7 minutes. Season with salt.
Cook almonds in remaining 1/2 tablespoon oil in a small heavy skillet over medium-low heat, stirring frequently, until golden, 3 to 5 minutes. Sprinkle almonds over chard.