PREHEAT OVEN & PREP YOUR PAN. Preheat oven to 375° F. Line a sheet pan with parchment paper for easy clean up.
PRE-TOAST CHIPS. Spread tortilla chips into a single layer on your baking sheet, trying to make sure all the little gaps are filled in the best you can. (That way the toppings end up on the chips not the pan!) Sprinkle chips with ½ cup grated cheese (just a light layer!) and bake 5-8 minutes, or until toasted and the cheese is melted.
WHILE CHIPS TOAST, PREP CHICKEN. In a medium bowl, combine shredded chicken with ½ cup BBQ sauce. Toss gently with a fork until the chicken is evenly coated.
BUILD NACHOS & BAKE. When the chips are toasted, top chips with chicken, then top chicken with remaining 1 ½ cups cheese. Add pickled jalapeño slices, if desired, then bake another 5-8 min, or until the cheese if fully melted and bubbly.
GARNISH & SERVE. When the nachos are done, sprinkle them with cilantro and red onion, as desired, along with a sprinkle of black pepper. Drizzle with an extra 2-3 TBSP BBQ Sauce & serve.