Bring a large pot of water to a rapid boil. Season generously with a couple tablespoons of Kosher salt, then add the pasta. Cook according to package directions until al dente. Drain the pasta over a colander. While the pasta cooks, make the sauce.
Add unsalted butter to a large pan with deep sides set over medium heat. Cook, stirring occasionally, until the butter turns foamy and is a deep golden brown color.
To the browned butter, add canned pumpkin purée. Cook, stirring occasionally, until well mixed and homogenous.
To this, add the cooked, drained pasta, mascarpone cheese, Parmesan, chopped sage leaves, a pinch of ground cinnamon, and the reserved pasta water. Adjust the heat to medium, then stir until very well mixed.
Turn the heat off, then add large egg yolks to the pasta and stir vigorously to incorporate into the sauce. Taste, adjust seasoning, adding Kosher salt as needed, then transfer to serving bowls. Enjoy!