To make the filling: Blend next 7 ingredients in processor.
Set mixture aside.
To assemble: Lay 1 dough sheet on lightly floured surface.
Mound level teaspoons of filling at 2-inch intervals, leaving 1/2-inch border along edges.
Brush dough between filling and along edges with water.
Top with second sheet, pressing around filling to seal.
Trim around filling using pastry cutter to create ravioli.
Arrange ravioli on lightly floured waxed paper.
Repeat with remaining dough.
Let ravioli dry until leathery around edges.
(Can be prepared to this point up to 1 day ahead and refrigerated.)
To cook and serve: Stir 2 tablespoons olive oil into large pot of boiling salted water.
Add ravioli (in batches if necessary) and cook until just tender but firm to bite, about 8 minutes.
Transfer to bowl.
Add butter and toss well.
Divide among 8 plates.
Sprinkle each with freshly grated Parmesan cheese if desired.
Top with freshly ground pepper.