Boil the ravioli al dente, according to package instructions. Drain, reserving about 1 cup of pasta water, and set aside.
In a large sauté pan, melt the butter over low heat. Add the minced garlic and sauté until fragrant, stirring regularly.
Stir in the nutmeg, increase the heat to medium-low, and add the pumpkin puree. Stir until warmed through, about 3 minutes.
Slowly whisk in the half and half and add the minced herbs, grated Parmesan, salt and pepper. Whisk until thickened.
Add the cooked ravioli to the sauce and stir to coat. If the sauce is too thick, slowly add pasta water until you reach desired consistency.
Spoon ravioli onto plates and garnish with grated Parmesan, toasted walnuts, and fresh herbs as desired.