Lightly grease slow cooker with cooking spray and trim pork shoulder of any excess fat.
Mix the oil with the seasoning mix, and carefully brush all over the meat.
Pour the chicken stock over the meat.
Cook on high for 4-5 hours, or low for 8-9 hours, until tender.
Remove from slow cooker and shred the meat with two forks.
To make the nachos, pre-heat the oven to 190°C and lightly grease a baking dish.
Spread half of the tortillas evenly across the dish and layer on half of
the pulled pork, cheese, and jalapeños, if using. Repeat with the
other half, then place into the oven.
Bake for 10 minutes or until the cheese has melted.
Serve with sour cream, salsa, guacamole, lettuce, etc.