Place 4 microwave-safe bowls on the counter. Lay a single layer of corn chips over the bottom of each bowl.
Top corn chips with half the salsa, half the shredded chicken and half the cheese. Microwave each bowl for 60 seconds or until the cheese has begun to melt.
Create a second layer by topped the bowls with the remaining corn chips, salsa, shredded chicken and cheese. Microwave each bowl for 60-90 seconds, or until the cheese is melted and the chicken is heated through.
Top each bowl with handfuls of shredded lettuce, avocado, tomato, a sprinkle of spring onions and a spoonful of sour cream. Serve immediately.
Note: the double-layer of nachos is a substantial-sized serve. For small children, a single layer may suffice.