Prepare the breadcrumbs: Heat the olive oil in a large skillet over medium-high heat. Add the garlic and cook, stirring, until fragrant, about 30 seconds. Immediately add the breadcrumbs and salt. Cook, stirring occasionally, until toasted, about 2 minutes. Transfer to a bowl and let cool for 5 minutes. Add the lemon zest, Parmesan and parsley. Set aside.
Meanwhile, cook the pasta: Bring a large pot of salted water to a boil. Add the spaghetti and cook according to the package instructions, until al dente.
While the pasta cooks, combine the ricotta, Parmesan, cream and 1/2 teaspoon salt in a food processor. Process until super creamy, about 30 seconds. Set aside.
Drain the spaghetti, leaving behind 1/2 cup of the cooking water in the pot. Add the butter to the pot and bring to a simmer. Add the spaghetti and the ricotta mixture. Remove from the heat and stir vigorously with a pair of tongs until the ricotta and pasta water combine to make a smooth, velvety sauce. Season with a good amount of black pepper.
Divide the pasta among serving bowls and top each with a hearty sprinkle of the breadcrumbs.