1. In a small bowl, combine pumpkin puree, 1/4 cup Parmesan, salt, and pepper.
2. Lay 8 of the wonton wrappers on a clean work surface, and spoon 1 Tbs. filling into the center of each wrapper.
3. Use your finger to moisten the edges of each wrapper with water and lay a second wrapper over the filling; use a fork to crimp the edges and seal. Repeat with the remaining filling and wrappers. Cook ravioli in a large saucepan of salted simmering water, working in batches if necessary, about 5 minutes per batch. Drain and set aside.
4. Meanwhile, melt the butter in a large skillet. Cook over medium heat until the butter begins to brown, 3 to 4 minutes. Remove from the heat and add the sage leaves and lemon juice. Place 4 ravioli in each plate and drizzle with the butter-sage sauce and sprinkle with the remaining cup Parmesan cheese.