Cook the pasta according to the package directions. Drain the pasta, reserving 1 cup of the cooking water. Return the pasta to the pot.
Meanwhile, heat the oil in a large skillet over medium-high heat. Add the onions and ½ teaspoon each salt and pepper and cook, stirring often, until tender, 8 to 10 minutes. Add to the pasta along with the olives, almonds, lemon juice, Parmesan, ½ teaspoon salt, ¼ teaspoon pepper, and the cooking liquid and toss to combine. Transfer to a platter, dollop with the ricotta, drizzle with olive oil, and sprinkle with additional Parmesan and pepper.