Fill a large pot with lightly salted water and bring to a rolling boil. Stir in ravioli and return to a boil. Cook uncovered, stirring occasionally, until ravioli float to the top and filling is hot, about 6 to 8 minutes. Drain.

Melt mascarpone cheese, butter, and a pinch of black pepper in a saucepan over medium heat.

Stir milk, pumpkin, Pecorino Romano cheese, brown sugar, cinnamon, 2 teaspoons salt, and nutmeg into the mascarpone cheese mixture. Bring to a boil, reduce heat to low, and simmer until sauce thickens, about 5 to 10 minutes.