In a large pan over medium heat, mix the dry white wine, shallot, rosemary sprig, and whole black peppercorns. Cook until the mixture reduces to about 1 tablespoon of liquid, about 3-5 minutes.
Pour in the vegetable stock, allowing it to reduce by half. Strain the solids from the sauce and discard them, which takes about 15 minutes.
Return the liquid to the pan, continue to reduce, then stir in the heavy cream. Keep an eye on its thickness while the pasta cooks.
In a separate pot, boil salted water. Carefully add the butternut squash ravioli and cook until they float, which takes 2-5 minutes, depending on whether they're fresh or frozen.
In a small pan over medium-high heat, melt the unsalted butter. Add the panko breadcrumbs and toast until they're lightly browned, then set aside.
Stir finely chopped rosemary, freshly grated Parmesan cheese, and black pepper into the cream sauce. Adjust seasoning to taste, then gently coat the cooked ravioli in the sauce, finishing with the toasted panko on top.
