Spinach and Ricotta Gnudi with Warm Butter Sauce

Name: Spinach and Ricotta Gnudi with Warm Butter Sauce
Ingredients: 1 pound cow's milk ricotta, drained in a strainer for at least 2 hours; 1/4 cup spinach, sauteed and finely chopped; 1/2 cup grated Parmesan, plus more for serving; 4 tablespoons all-purpose flour; 3 tablespoons panko breadcrumbs; Pinch grated nutmeg; 1 large egg; 1 large egg yolk; Kosher salt and freshly ground black pepper; Extra-virgin olive oil, for serving; 1 tablespoon cornstarch; 3 sticks (1 1/2 cups) unsalted butter, cut into chunks; Kosher salt