Preparation

• 1 FOR RAVIOLI: Place pumpkin in medium bowl.
• 2 Whisk in ground walnuts and ricotta to blend well. Season to taste with salt. Whisk egg into pumpkin mixture to blend.
• 3 Sprinkle two baking sheets with semolina. Follow method for making Fresh Pasta and forming 4- to 5-inch wide pasta sheets; do not dry pasta. Working with one pasta sheet at a time, lay sheet on work surface (cover remaining sheets with damp kitchen towel to keep moist).
• 4 Spoon generous teaspoonfuls pumpkin mixture on lower half of pasta sheet, spacing mounds 3/4-inch apart. Fold top half of pasta sheet over filling so the edges can meet. Press between mounds of filling so dough sticks together, removing as much air as possible between layers. Press edges together firmly.
• 5 Using pasta cutter, cut between mounds to form ravioli; trim any uneven edges. If dough is too dry, brush edges and between mounds of filling very lightly with water before folding dough over filling to help dough stick together. Transfer ravioli to prepared baking sheets. Repeat with remaining pasta sheets and pumpkin filling. Let ravioli rest 15 minutes.
• 6 MEANWHILE, PREPARE SAUCE: Melt butter and creme fraiche in heavy small saucepan, over low heat. Whisk together; add sage. Keep warm over very low heat.
• 7 TO SERVE: Working in batches, cook ravioli in large pot of boiling salted water until ravioli float to surface and are tender but still firm to bite, about 3 minutes. Drain.
• 8 Transfer ten ravioli to each of six warm pasta bowls. Spoon sauce over ravioli. Sprinkle with finely chopped walnuts and serve.
• 9 FRESH PASTA: MAKING DOUGH: Sift flour onto large flat work surface.
• 10 Form well in center of flour. Place eggs and salt in well; whisk lightly with fork to blend. Using fork, gradually mix flour from inside walls of well into egg mixture to form coarse dough. Knead until dough is satiny and surface is almost smooth, about 4 minutes. Form dough into ball. Cover with plastic wrap and let dough rest at least 30 minutes and up to 3 hours.
• 11 KNEADING DOUGH: Set rollers for pasta machine, on widest setting.
• 12 Using dough cutter, cut dough into eight equal pieces. Form each piece into ball; flatten into disks. Run one dough disk through rollers, dusting lightly with flour if dough sticks (keep remaining dough disks covered). Working on lightly floured surface, fold dough into thirds as for business letter. Pass dough, edges first, through rollers again. Repeat process six times, keeping rollers at widest setting and lightly dusting rollers with flour if dough sticks.
• 13 FORMING PASTA SHEETS: Adjust width of rollers to next smaller setting, and pass dough through rollers. Continue adjusting roller width to smaller settings, running dough through each setting without folding, and dusting rollers very lightly with flour if necessary until long dough sheet forms, about 24 to 30 inches long.
• 14 Hang strips over pasta drying rack, just until pasta is slightly dry, about 10 minutes (pasta should not be brittle or wet). Repeat kneading remaining dough disks and forming them into pasta sheets.
• 15 FOR FRESH PASTA WITH GARLIC: Mix 1 minced large garlic clove into egg and salt mixture in center of flour well. For Fresh Pasta with Thyme: Mix 2 teaspoons fresh thyme leaves into flour before blending with egg and salt mixture.