Mash pumpkin purée, Parmesan and lemon zest in a medium bowl. Season to taste with salt, pepper and cayenne.
Arrange wonton wrappers on a work surface. Brush edges with lightly beaten egg.
Place 1 teaspoon filling on bottom half; fold top half over, gently pressing edges to seal.
Boil ravioli in salted water until just tender, about 3 minutes.
Melt butter with purèe fraîche in a sauté pan. Add 2 tablespoons of reserved pasta water or more if needed; add cooked ravioli and toss to coat.
Top with grated Parmesan and toasted pumpkin seeds.
*Recipe adapted from Bon Appetit, 2011