Heat a large dutch oven over medium heat. Add olive oil. Once oil is hot, add onion and saute until soft. Add cumin, garlic powder chili powder cayenne, salt and pepper. Stir until spices coat the onions and are fragrant. Meanwhile, in a large measuring cup (or small bowl), combine the masa with 2 cups of chicken stock. Whisk constantly until it become thick, about two minutes. To the soup pot, add in remaining chicken stock, enchilada sauce, canned tomatoes, and canned green chilies. Slowly whisk in masa-stock mixture. Stir until soup becomes thick. Stir in shredded chicken and Velveeta. Taste and season with salt and pepper as needed. Top with your choice of diced jalapenos, cilantro, and sour cream.