To make Carnitas: 

Spray or grease a large slow cooker with cooking spray or oil. Place the pork into the slow cooker and sprinkle over the taco seasoning mix, reserving 1 tablespoon for the nachos. Pour over the chicken stock then cover and cook on a High heat setting for 4-5 hours, or Low heat setting 8-9 hours, or until tender. Remove from slow cooker and shred with fork, discarding any excess fat.

To make Nachos: 

Preheat the oven to 200°C (180°C for fan assisted ovens), gas mark 6. Grease a large baking dish (about 1.5 litres) with oil and spread half of the Nachips™ into the dish.

In a small bowl, mix the cheese and reserved tablespoon of taco seasoning mix. Sprinkle one third of cheese mixture over Nachips™. Spoon half of reserved carnitas mixture over the Nachips™ followed by half of the jalapeños. Repeat layers ending with remaining cheese.

Bake for 10-12 minutes or until the cheese is melted. Top with the spring onions and serve with soured cream.