This fresh, light mole contrasts with more traditional, time-consuming versions. It whips up super-quick but retains an authentic touch. Green pumpkin seed moles are similar to sauces the Aztecs made before the Spanish Conquest.
Coat an unheated large skillet with cooking spray. Preheat skillet over medium heat. Add chicken; cook for 10 to 12 minutes or until tender and no longer pink, turning once. Remove chicken; keep warm.
For mole, in the same skillet cook onion and garlic in hot oil over medium heat about 5 minutes or until onion is tender.
In a blender or food processor combine onion mixture, tomatillos, the 1/3 cup toasted pumpkin seeds, chile peppers, broth, cilantro, and salt. Cover and blend or process with several on-off turns to make a coarse puree. Transfer mole to skillet; heat through.
To serve, spoon mole over chicken breasts. If desired, sprinkle with additional toasted pumpkin seeds.