Blue Cheese Ravioli with Onion Sauce
- 4 tablespoons butter, divided
- 3/4 cup (or more) vegetable broth
- 1 1/2 cups all purpose flour
- 1 cup whole-milk ricotta cheese, well drained, squeezed dry in towel
- 1/2 cup crumbled blue cheese (about 2 ounces)
- 2 tablespoons freshly grated Parmesan cheese
- 1 large egg white, whisked until foamy
Melt 3 tablespoons butter in heavy medium skillet over medium heat. Mix in onions. Cover; cook until softened but not brown, stirring occasionally, about 10 minutes. Add 3/4 cup broth; simmer until onions are tender, about 6 minutes. Puree onions in processor until smooth. Pour into small saucepan. Add 1 tablespoon butter. Thin with more broth, if desired. DO AHEAD Can be made 1 day ahead. Cover; chill.
Mix flour and salt in large bowl; make well in center. Add eggs, yolks, and 1 tablespoon water to well; stir to blend. Gradually stir flour into egg mixture. Knead dough in bowl until shaggy, sticky dough forms, about 5 minutes. Turn dough out onto lightly floured work surface and knead until smooth, about 10 minutes. Gather dough into ball. Cover with plastic and let rest 1 hour at room temperature.
Cook butter in heavy small saucepan over medium heat until brown, about 3 minutes. Pour into small bowl; cool. Mix in ricotta, blue cheese, Parmesan, salt, pepper, and egg yolk.
Divide dough into 4 equal pieces. Cover 3 pieces with plastic wrap. Set pasta machine to widest setting. Flatten 1 dough piece into rectangle; run through machine. Fold in half crosswise (end to end) and run through again. Continue, adjusting machine to narrower settings after every 2 passes and dusting with flour as needed to keep from sticking, until pasta sheet is 24 inches long (scant 1 1/6 inch thick). Using 2-1/2-inch round cutter, cut out 12 to 14 rounds. Brush half of each round lightly with egg white.
Drop 1 teaspoon filling into center of each round; lift sides of round up over filling to meet at center; pinch to seal along seam, forming dumpling. Repeat with remaining rounds. Place in single layer on lightly floured parchment-lined baking sheets. Repeat with remaining dough. DO AHEAD Can be made 6 hours ahead; chill.
Working in 2 batches, cook pasta in large deep skillet of boiling salted water until just tender, about 5 minutes. Using slotted spoon, transfer to large bowl. Drizzle with 1 tablespoon olive oil; toss gently.
Rewarm sauce; drizzle onto each plate. Top with ravioli and garnish.