Toast the Panko: In a medium skillet, melt 1/2 tablespoon butter over medium heat. Add panko breadcrumbs and cook, stirring frequently, until they turn a beautiful golden brown. Transfer the toasted panko to a small, heat-proof bowl and set aside. Carefully wipe the skillet clean with paper towels.
Boil Water for Ravioli: Bring a large pot of lightly salted water to a rolling boil for your ravioli.
Start the Browned Butter Sauce: While the water heats, melt the remaining 8 tablespoons of butter in the now-clean skillet over medium heat.
Brown the Butter: Continue to cook and stir the butter. It will foam, then start to deepen in color, turning a lovely amber brown with a nutty aroma (this takes about 4-5 minutes). Watch it closely to prevent burning!
Add Nuts and Sage: Once the butter is lightly browned, stir in the chopped nuts and fresh sage leaves. Continue to cook for another 2 minutes until the butter is slightly foamy and darker brown.
Infuse with Garlic: Add the minced garlic and cook for about 1 minute more, until the butter has a rich, nutty scent and the milk solids at the bottom are golden brown (be careful not to burn it – it should be amber, not dark brown).
Set Aside Sauce: Pour the browned butter mixture into a heat-proof dish and set it aside.
Cook Ravioli: Cook the ravioli in the boiling water according to package directions until al dente (firm to the bite). Before draining, reserve about 1/4 cup of the pasta water. Then, drain the ravioli well.
Combine and Finish: Return the cooked ravioli to the empty pot (off the heat) or a large serving bowl. Pour the browned butter sage sauce over the ravioli. Add the fresh lemon juice and 2 tablespoons of the reserved pasta water. Gently toss everything together until the ravioli is evenly coated, adding a touch more pasta water if the sauce seems too thick.
Serve: Dish out immediately, garnished generously with the toasted panko breadcrumbs and shredded Pecorino Romano or Parmesan cheese. Enjoy your comforting, flavorful meal!