- Put all ingredients in food processor. Pulse a couple of times, being careful not to overwork the ingredients.
- Empty dough onto a cutting board, press together with hands, and wrap in plastic wrap. Let dough rest a minimum of one hour or overnight in the refrigerator.
- Preheat oven to 350 degrees. Roast sweet potatoes until tender. Peel and let cool.
- Heat butter in a small sauté pan until foamy, add onions, and sauté until translucent.
- Add sweet potatoes, remove form fire, and smash with a fork until smooth. Set aside to cool.
- Put sweet potato mixture in a medium bowl and add remaining ingredients. Mix well, season with salt and pepper, and store in refrigerator until ready to assemble pasta.
- Set up pasta maker on a sturdy work surface and dust worktop with a little durum flour.
- Roll dough through machine, progressively getting thinner with each pass until dough is thin enough that you can just barely see your hand through it. Dust work surface generously with flour again. Lay dough down out on work surface and cut it in half. Top layer should be gently folded, held to side, and covered with a towel.
- Brush bottom layer with an egg wash mixture (1 egg, ¼ cup water) and scoop filling in tablespoon-sized piles evenly distributed across sheet of pasta, leaving an inch between each pile.
- Carefully line up and lay top layer of pasta over top of piles. Use your fingers to seal around each pile while pushing the air out toward edges. Using a fluted pasta cutter, cut ravioli into individual pieces. Transfer onto a cookie sheet that has been lightly dusted with cornmeal and store in refrigerator until ready to cook and serve. If you are going to use the next day, cover them with a dry, clean dishtowel.
- Cook ravioli in a large pot of salted water for 2−4 minutes (depends on thickness of dough). Test for doneness by pulling a piece out and squeezing edge to be sure it is tender.
- Meanwhile, heat butter in a large sauté pan until milk solids have just started to turn brown. Slide pan away from the heat to prevent a flare up and add pecans and stock to pan and swirl.
- Remove pasta from water and put directly into sauce. (Note: Use a wire skimmer or slotted spoon. Do not pour pasta into a colander and risk breaking what you’ve worked so hard to make!)
- Add herbs and cooked ravioli and simmer gently for 20−30 seconds, tossing pasta gently.
- Spoon pasta onto plates. Add remaining butter sauce on and around ravioli. Sprinkle liberally with grated Parmigiano. Enjoy immediately!