Bring chicken stock to boil in deep skillet. Season chicken with salt and pepper. Add to broth. Cover and cook until chicken is opaque in center, about 8 minutes. Transfer chicken to work surface; reserve stock. Cool chicken. Shred.

Heat 2 tablespoons oil in heavy large saucepan over medium heat. Add 1 chopped onion. Saute until soft. Add garlic and saute until fragrant, about 2 minutes. Add salsa and reserved stock. Simmer 10 minutes.

Pour 1 cup vegetable oil into large skillet. Heat over medium heat. When hot, fry tortillas in batches until golden brown and crisp. Using slotted spoon, transfer tortillas to paper towels and drain.

Add shredded chicken to salsa pot. Bring to boil. Add cilantro. Season to taste with salt and pepper. Stir in fried tortilla chips. Ladle into bowls. Sprinkle with cheese and finely chopped onion. Place dollop of crema in center and serve.

Place tomatillos, jalapenos and water in blender. Coarsely chop. Add onion, cilantro and salt. Puree until smooth, about 2 minutes. Transfer to medium saucepan. Simmer until reduced to 2 cups, about 10 minutes. Season with salt and pepper.