Season chicken breasts with salt, pepper, garlic, mustard and Worcestershire sauce and then place in a resealable bag.
Place chicken in the fridge to marinate for 1-2 hours.
Remove chicken breasts from bag and place in a baking dish or tray, cover with aluminum foil and place in a preheated oven at 400. Cook until juices run clear (approx. 1 hour).
Once chicken breasts are cooked shred using a spoon and fork, add barbecue sauce, mix thoroughly and then cover with foil to keep warm.
Arrange chips on a serving plate or dish, and then top with shredded chicken.
Mix the cheddar and pepper jack cheese together and then sprinkle half of the cheese over the chicken until you have a layer of cheese.
Sprinkle jalapeño slices on top of cheese, and then finish off with the rest of the cheese.