Char poblanos over gas flame or in broiler until blackened on all sides. Place in paper bag; seal and let stand at room temperature 15 minutes. Peel and seed peppers; chop.

Heat oil in large skillet over medium heat. Add onion and corn and cook until onion begins to brown, about 4 minutes. Reduce heat to low; cook until vegetables are very soft and onion is brown, stirring often, about 15 minutes. Add chopped poblanos. Season with salt and pepper.

Lightly sprinkle rimmed baking sheet with cornmeal. Mix huitlacoche and queso fresco in a medium bowl. Arrange 18 wonton wrappers on work surface. Place 1 heaping teaspoon huitlacoche filling in center of each wrapper. Using pastry brush, paint edges of wrappers with beaten egg. Top each with an additional wonton wrapper. Using round cookie cutter, cut raviolis into rounds. Place on prepared baking sheet. Repeat with remaining wrappers and filling.

Cook butter in large skillet over medium heat until beginning to brown, stirring occasionally, about 4 minutes. Turn off heat and stir in pepitas.

Cook ravioli in pot of gently boiling salted water until tender, about 4 minutes. Drain well. Transfer ravioli to skillet with browned butter. Toss over medium heat.

Meanwhile, re-warm bell pepper mixture; divide among 6 plates. Using slotted spoon, top peppers on each plate with 3 ravioli. Drizzle with any remaining browned butter. Sprinkle with additional queso fresco and green onions and serve.