Bring a large pot of water to boil for your pasta, and season generously with salt.
Add a 1/3 cup of cold water and add to a large frying or sauté pan over a medium heat.
Once the water is boiling, start to drop in a couple of cubes of cold butter, swirling the pan and whisking continuously until the butter is emulsified and uniform.
Once you have a stable emulsion, continue adding the rest of the butter, whisking, whirling and swirling.
Throw in the sliced asparagus, season with a touch of salt.
Keep the pan on the most tiny of flames to keep warm, stirring occasionally.
Drop the ravioli into the boiling water and cooking for 2 minutes or longer if you are cooking from frozen.
Scoop out with a slotted spoon or spider, and drop directly into the butter sauce.
Gently whirl and toss to coat all of the ravioli in the sauce.
Allow 8-10 ravioli per person.
Serve with grated Parmigiano Reggiano.